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Sample records for photochemically active nanoparticles

  1. Silver nanoparticles with gelatin nanoshells: photochemical facile green synthesis and their antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Pourjavadi, Ali; Soleyman, Rouhollah

    2011-10-01

    In the current study, a facile green synthesis of silver-gelatin core-shell nanostructures (spherical, spherical/cubic hybrid, and cubic, DLS diameter: 4.1-6.9 nm) is reported via the wet chemical synthesis procedure. Sunlight-UV as an available reducing agent cause mild reduction of silver ions into the silver nanoparticles (Ag-NPs). Gelatin protein, as an effective capping/shaping agent, was used in the reaction to self-assemble silver nanostructures. The formation of silver nanostructures and their self-assembly pattern was confirmed by SEM, AFM, and TEM techniques. Further investigations were carried out using zeta-potential, UV-Vis, FTIR, GPC, and TGA/DTG/DTA data. The prepared Ag-NPs showed proper and acceptable antimicrobial activity against three classes of microorganisms ( Escherichia coli Gram-negative bacteria, Staphylococcus aureus Gram-positive bacteria, and Candida albicans fungus). The antibacterial and antifungal Ag-NPs exhibit good stability in solution and can be considered as promising candidates for a wide range of biomedical applications.

  2. Morphological transformations of silver nanoparticles in seedless photochemical synthesis

    NASA Astrophysics Data System (ADS)

    Lu, Ya; Zhang, Congyun; Hao, Rui; Zhang, Dongjie; Fu, Yizheng; Moeendarbari, Sina; Pickering, Christopher S.; Hao, Yaowu; Liu, Yaqing

    2016-05-01

    Photochemical synthesis is an easily controlled and reliable method for the fabrication of silver (Ag) nanoparticles with various morphologies. In this work, we have systematically investigated the seedless photochemical synthesis of anisotropic Ag nanoparticles with and without PVP as surface capping agent. The time evolution of anisotropic Ag nanoparticles during the synthesis process are studied using UV-visible spectra, optical images and transmission electron microscopy. The results show that the light irradiation precisely controls the start and termination of the reaction, and the presence or absence of PVP greatly affects the morphology evolution of anisotropic Ag nanoparticles. With PVP as the surface capping agent, Ag nanoparticles grow into decahedra or prism by the deposition of Ag atoms on {111} or {110} facets through epitaxial growth. However, a different morphology evolution could happen when Ag nanoparticle is synthesized without PVP as surface capping agent. In this case, Ag nanoparticles can fuse into the decahedrons through an edge-selective particle fusion mechanism, which involves attachment, rotation and realignment of Ag nanoparticles. This process was evidenced with HRTEM images at the different stages of the transformation from Ag colloid to decahedra nanoparticles. Oriented attachment and Ostwald ripening also play important role in the transformation process.

  3. Metal hybrid nanoparticles for catalytic organic and photochemical transformations.

    PubMed

    Song, Hyunjoon

    2015-03-17

    In order to understand heterogeneous catalytic reactions, model catalysts such as a single crystalline surface have been widely studied for many decades. However, catalytic systems that actually advance the reactions are three-dimensional and commonly have multiple components including active metal nanoparticles and metal oxide supports. On the other hand, as nanochemistry has rapidly been developed and been applied to various fields, many researchers have begun to discuss the impact of nanochemistry on heterogeneous catalysis. Metal hybrid nanoparticles bearing multiple components are structurally very close to the actual catalysts, and their uniform and controllable morphology is suitable for investigating the relationship between the structure and the catalytic properties in detail. In this Account, we introduce four typical structures of metal hybrid nanoparticles that can be used to conduct catalytic organic and photochemical reactions. Metal@silica (or metal oxide) yolk-shell nanoparticles, in which metal cores exist in internal voids surrounded by thin silica (or metal oxide) shells, exhibited extremely high thermal and chemical stability due to the geometrical protection of the silica layers against the metal cores. The morphology of the metal cores and the pore density of the hollow shells were precisely adjusted to optimize the reaction activity and diffusion rates of the reactants. Metal@metal oxide core-shell nanoparticles and inverted structures, where the cores supported the shells serving an active surface, exhibited high activity with no diffusion barriers for the reactants and products. These nanostructures were used as effective catalysts for various organic and gas-phase reactions, including hydrogen transfer, Suzuki coupling, and steam methane reforming. In contrast to the yolk- and core-shell structures, an asymmetric arrangement of distinct domains generated acentric dumbbells and tipped rods. A large domain of each component added multiple

  4. New photochemical tools for controlling neuronal activity

    PubMed Central

    Kramer, Richard H.; Fortin, Doris L.; Trauner, Dirk

    2009-01-01

    Neurobiology has entered a new era in which optical methods are challenging electrophysiological techniques for their value in measuring and manipulating neuronal activity. This change is occurring largely because of the development of new photochemical tools, some synthesized by chemists and some provided by nature. This review is focused on the three types of photochemical tools for neuronal control that have emerged in recent years. Caged neurotransmitters, including caged glutamate, are synthetic molecules that enable highly localized activation of neurotransmitter receptors in response to light. Natural photosensitive proteins, including channelrhodopsin-2 and halorhodopsin, can be exogenously expressed in neurons and enable rapid photocontrol of action potential firing. Synthetic small-molecule photoswitches can bestow light-sensitivity on native or exogenously expressed proteins, including K+ channels and glutamate receptors, allowing photocontrol of action potential firing and synaptic events. At a rapid pace, these tools are being improved and new tools are being introduced, thanks to molecular biology and synthetic chemistry. The three families of photochemical tools have different capabilities and uses, but they all share in enabling precise and non-invasive exploration of neural function with light. PMID:19828309

  5. Heparin Assisted Photochemical Synthesis of Gold Nanoparticles and Their Performance as SERS Substrates

    PubMed Central

    Rodríguez-Torres, Maria del Pilar; Díaz-Torres, Luis Armando; Romero-Servin, Sergio

    2014-01-01

    Reactive and pharmaceutical-grade heparins were used as biologically compatible reducing and stabilizing agents to photochemically synthesize colloidal gold nanoparticles. Aggregates and anisotropic shapes were obtained photochemically under UV black-light lamp irradiation (λ = 366 nm). Heparin-functionalized gold nanoparticles were characterized by Scanning Electron Microscopy and UV-Vis spectroscopy. The negatively charged colloids were used for the Surface Enhanced Raman Spectroscopy (SERS) analysis of differently charged analytes (dyes). Measurements of pH were taken to inspect how the acidity of the medium affects the colloid-analyte interaction. SERS spectra were taken by mixing the dyes and the colloidal solutions without further functionalization or addition of any aggregating agent. PMID:25342319

  6. An efficient photochemical route to Pd nanoparticles; application to the one-step synthesis of Pd@polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Wolak, Séverine; Vidal, Loïc; Becht, Jean-Michel; Michelin, Laure; Balan, Lavinia

    2016-08-01

    We have developed a facile, efficient, low cost and ‘green’ photochemical approach to preparing surfactant-free Pd nanoparticles and Pd-immobilized@acrylate photo-polymer films at room temperature, under air and without any additional treatment. The reaction system only includes a photo-initiator used as a generator of free radicals and a Pd(II) salt. In ethanol solution, the photochemical reduction of Pd(II) to Pd(0) generates very small metal particles with a narrow size distribution (2-4 nm). Furthermore, we have shown that the formation of Pd nanoparticles from a Pd(II) salt can be reversible thus allowing easy handling and safe storage with the possibility of generating the nanoparticles just before use. In the presence of an acrylate bifunctional monomer, Pd@polymer film was obtained through a ‘one-pot, one-step’ process resulting from a simultaneous photo-reduction of Pd(II) and photo-polymerization of acrylate units. The simultaneous generation of a 3D polymer network and of metal particles leads to a homogeneous distribution of Pd nanoparticles in the photo-polymer matrix with an average diameter of approximately 3.7 ± 1.1 nm. Such as-prepared Pd@polymer films were found to efficiently catalyze the Mizoroki-Heck reaction in the presence of only 0.9 mequiv. of supported palladium. The major interest of this arrangement is its recoverability and reusability, which makes it very attractive both from a practical and economical viewpoint. Finally, it is worth noting that this innovation offers a great advantage over concurrent methods in that it is simply generated within minutes, it is highly stable, and there is sharp monodispersity in the size of the Pd nanoparticles that can be stored for months without alteration of their physico-chemical properties and catalytic activity.

  7. Photochemical internalization-mediated nonviral gene transfection: polyamine core-shell nanoparticles as gene carrier

    NASA Astrophysics Data System (ADS)

    Zamora, Genesis; Wang, Frederick; Sun, Chung-Ho; Trinidad, Anthony; Kwon, Young Jik; Cho, Soo Kyung; Berg, Kristian; Madsen, Steen J.; Hirschberg, Henry

    2014-10-01

    The overall objective of the research was to investigate the utility of photochemical internalization (PCI) for the enhanced nonviral transfection of genes into glioma cells. The PCI-mediated introduction of the tumor suppressor gene phosphatase and tensin homolog (PTEN) or the cytosine deaminase (CD) pro-drug activating gene into U87 or U251 glioma cell monolayers and multicell tumor spheroids were evaluated. In the study reported here, polyamine-DNA gene polyplexes were encapsulated in a nanoparticle (NP) with an acid degradable polyketal outer shell. These NP synthetically mimic the roles of viral capsid and envelope, which transport and release the gene, respectively. The effects of PCI-mediated suppressor and suicide genes transfection efficiency employing either "naked" polyplex cores alone or as NP-shelled cores were compared. PCI was performed with the photosensitizer AlPcS2a and λ=670-nm laser irradiance. The results clearly demonstrated that the PCI can enhance the delivery of both the PTEN or CD genes in human glioma cell monolayers and multicell tumor spheroids. The transfection efficiency, as measured by cell survival and inhibition of spheroid growth, was found to be significantly greater at suboptimal light and DNA levels for shelled NPs compared with polyamine-DNA polyplexes alone.

  8. Magnetic poly(PEGMA-MAA) nanoparticles: photochemical preparation and potential application in drug delivery.

    PubMed

    Sun, Han-Wen; Zhang, Lian-Ying; Zhu, Xin-Jun; Wang, Xin-Fang

    2009-01-01

    Poly(PEGMA-MAA)-coated superparamagnetic nanoparticles were synthesized by in situ photochemical polymerization in magnetite aqueous suspension under UV irradiation. The magnetic poly(PEGMA-MAA) nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), photo correlation spectroscopy (PCS) and vibration sample magnetometry (VSM), respectively. The results indicated that the magnetic poly(PEGMA-MAA) nanoparticles were of regularly spherical shape and remained monodisperse. The average size measured in aqueous media was 96.4 nm, which was much bigger than that in dry state, the nanoparticles behaved superparamagnetic with saturated magnetization of 64.8 emu/g, the zeta potential was -18.3 mV at physiological pH 7.2, and the magnetic poly(PEGMA-MAA) nanoparticles had a high stability in vitro. A typical anti-inflammatory drug, ibuprofen, was used for drug loading, and the release behavior of ibuprofen in a simulated body fluid (SBF, pH 7.4) was studied. The results indicated that these novel magnetic nanoparticles had a high drug-loading capacity and favorable release properties for ibuprofen. The magnetic poly(PEGMA-MAA) nanoparticles are very promising for application in drug delivery.

  9. Photochemical and antimicrobial properties of silver nanoparticle-encapsulated chitosan functionalized with photoactive groups.

    PubMed

    Mathew, Thomas V; Kuriakose, Sunny

    2013-10-01

    Chitosan was functionalized with 4-((E)-2-(3-hydroxynaphthalen-2-yl)diazen-1-yl)benzoic acid by the coupling of the hydroxyl functional groups of chitosan with carboxylic acid group of the dye by DCC coupling method. The silver nanoparticles were prepared by sol-gel method of nanoparticle synthesis. Silver nanoparticle-encapsulated functionalized chitosan was prepared by the phase transfer method. The products were characterized by FTIR, UV-Vis, fluorescence and NMR spectroscopic methods and by SEM and TEM analysis. The photochemical properties of silver nanoparticle-encapsulated chitosan functionalized with 4-((E)-2-(3-hydroxynaphthalen-2-yl)diazen-1-yl)benzoic acid was studied in detail. The light-fastening properties of the chromophoric system was enhanced when attached to chitosan, and it can be further improved by the encapsulation of silver nanoparticles. The antibacterial analysis of silver nanoparticle-encapsulated functionalized chitosan was carried out against Staphylococcus aureus and Escherichia coli and against fungal species such as Aspergillus flavus and Aspergillus terreus. This study showed that silver nanoparticles-encapsulated functionalized chitosan can be used for antibacterial and antifungal applications.

  10. Global emissions and models of photochemically active compounds

    SciTech Connect

    Penner, J.E.; Atherton, C.S.; Graedel, T.E.

    1993-05-20

    Anthropogenic emissions from industrial activity, fossil fuel combustion, and biomass burning are now known to be large enough (relative to natural sources) to perturb the chemistry of vast regions of the troposphere. A goal of the IGAC Global Emissions Inventory Activity (GEIA) is to provide authoritative and reliable emissions inventories on a 1{degree} {times} 1{degree} grid. When combined with atmospheric photochemical models, these high quality emissions inventories may be used to predict the concentrations of major photochemical products. Comparison of model results with measurements of pertinent species allows us to understand whether there are major shortcomings in our understanding of tropospheric photochemistry, the budgets and transport of trace species, and their effects in the atmosphere. Through this activity, we are building the capability to make confident predictions of the future consequences of anthropogenic emissions. This paper compares IGAC recommended emissions inventories for reactive nitrogen and sulfur dioxide to those that have been in use previously. We also present results from the three-dimensional LLNL atmospheric chemistry model that show how emissions of anthropogenic nitrogen oxides might potentially affect tropospheric ozone and OH concentrations and how emissions of anthropogenic sulfur increase sulfate aerosol loadings.

  11. Photochemically-assisted synthesis of non-toxic and biocompatible gold nanoparticles.

    PubMed

    Teixeira, Priscila R; Santos, Mayara S C; Silva, Ana Luísa G; Báo, Sônia N; Azevedo, Ricardo B; Sales, Maria José A; Paterno, Leonardo G

    2016-12-01

    This contribution describes the photochemically-assisted synthesis of aqueous colloidal suspensions of non-toxic and biocompatible spherical gold nanoparticles stabilized by branched polyethylenimine, or else Au-np-PEI. The method consists on 30min of photoexcitation (254nm, 16W) at room temperature of an aqueous diluted solution of chloroauric acid (HAuCl4) containing PEI. While the UV irradiation forms the [Au((3+))Cl4(-)]* excited species that succesively transforms into zero valent Au, PEI controls the nucleation step of nanoparticles formation. Varying the PEI to Au molar ratio permits one to tune the size of nanoparticles between 100nm to 8nm. The obtained colloidal suspensions display an intense plasmonic absorption band at 520-530nm and positive zeta potentials greater than +20mV. The cells viability for in vitro tests performed with human connective tissues and human breast adenocarcinoma (MCF-7) cell lines is over 80% and 90%, respectively, when they are incubated with Au-np-PEI formulations (25μgmL(-1)). The present photochemically-assisted synthesis is advantageous because it is fast and does not require for either hazardous or cytotoxic reductant agents and additional purification procedures.

  12. Synthesis of Monometallic (Au and Pd) and Bimetallic (AuPd) Nanoparticles Using Carbon Nitride (C3N4) Quantum Dots via the Photochemical Route for Nitrophenol Reduction.

    PubMed

    Fageria, Pragati; Uppala, Shravan; Nazir, Roshan; Gangopadhyay, Subhashis; Chang, Chien-Hsiang; Basu, Mrinmoyee; Pande, Surojit

    2016-10-04

    In this study, we report the synthesis of monometallic (Au and Pd) and bimetallic (AuPd) nanoparticles (NPs) using graphitic carbon nitride (g-C3N4) quantum dots (QDs) and photochemical routes. Eliminating the necessity of any extra stabilizer or reducing agent, the photochemical reactions have been carried out using a UV light source of 365 nm where C3N4 QD itself functions as a suitable stabilizer as well as a reducing agent. The g-C3N4 QDs are excited upon irradiation with UV light and produce photogenerated electrons, which further facilitate the reduction of metal ions. The successful formation of Au, Pd, and AuPd alloy nanoparticles is evidenced by UV-vis, powder X-ray diffraction, X-ray photon spectroscopy, and energy-dispersive spectroscopy techniques. The morphology and distribution of metal nanoparticles over the C3N4 QD surface has been systematically investigated by high-resolution transmission electron microscopy (HRTEM) and SAED analysis. To explore the catalytic activity of the as-prepared samples, the reduction reaction of 4-nitrophenol with excellent performance is also investigated. It is noteworthy that the synthesis of both monometallic and bimetallic NPs can be accomplished by using a very small amount of g-C3N4, which can be used as a promising photoreducing material as well as a stabilizer for the synthesis of various metal nanoparticles.

  13. Research on the photochemical kinetics process of gold nanoparticle-doped photopolymer system using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Ruoping; Yang, Jingliang; Li, Yanmeng; Han, Junhe; Huang, Mingju

    2016-10-01

    A photopolymer system doped with gold nanoparticles (Au NPs) was studied using Surface Enhanced Raman Scattering (SERS) technique in this work. In the system, polyvinyl alcohol is a binder, acrylamide and methylene-bisacrylamide are two monomers, methylene blue (MB) is a photosensitizer and triethanolamine is an initiator. Two types of Au NPs-- bare Au NPs with 13nm and 25nm diameter, and their corresponding SiO2 shell-isolated Au (Au@SiO2) NPs with 2nm shell thickness, were prepared and doped into the photopolymer for reducing the shrinkage of holograms. The shield of SiO2 shell avoids the dark reaction originating from electron transfer between Au NPs and MB molecules. More importantly, under 633nm laser excitation, the resonance Raman scattering of MB can be triggered, and the Raman signal of MB can be enhanced greatly due to the local enhanced electromagnetic field by Au@SiO2 NPs. Both of them made the in-situ Raman detection of the photopolymer more feasible. The experimental results not only show the excitation process of MB but also display the polymerization process of the photopolymer. In addition, the excitation rate of MB and the polymerization rate of monomers can also be obtained using their time Raman spectra. This provides an experimental tool for detecting the photochemical kinetics process of the photopolymer.

  14. Synthesis of Highly Active Sub-Nanometer Pt@Rh Core-Shell Nanocatalyst via a Photochemical Route: Porous Titania Nanoplates as a Superior Photoactive Support.

    PubMed

    Zhan, Wen-Wen; Zhu, Qi-Long; Dang, Song; Liu, Zheng; Kitta, Mitsunori; Suenaga, Kazutomo; Zheng, Lan-Sun; Xu, Qiang

    2017-02-02

    Sub-nanometer Pt@Rh nanoparticles highly dispersed on MIL-125-derived porous TiO2 nanoplates are successfully prepared for the first time by a photochemical route, where the porous TiO2 nanoplates with a relatively high specific surface area play a dual role as both effective photoreductant and catalyst support. The resulting Pt@Rh/p-TiO2 can be utilized as a highly active catalyst.

  15. Functional, photochemically active, and chemically asymmetric membranes by interfacial polymerization of derivatized multifunctional prepolymers

    DOEpatents

    Lonsdale, Harold K.; Wamser, Carl C.

    1990-01-01

    The preparation of a novel class of thin film membranes by interfacial polymerization is disclosed, said membranes incorporating as part of their polymeric structure the functionality of monomeric or oligomeric precursors. Specific embodiments include porphyrin and phthalocyanine derivatives that are photochemically or electrochemically active, as well as chemically asymmetric membranes.

  16. Functional, photochemically active, and chemically asymmetric membranes by interfacial polymerization of derivatized multifunctional prepolymers

    DOEpatents

    Lonsdale, H.K.; Wamser, C.C.

    1990-04-17

    The preparation of a novel class of thin film membranes by interfacial polymerization is disclosed, said membranes incorporating as part of their polymeric structure the functionality of monomeric or oligomeric precursors. Specific embodiments include porphyrin and phthalocyanine derivatives that are photochemically or electrochemically active, as well as chemically asymmetric membranes.

  17. Functional, photochemically active, and chemically asymmetric membranes by interfacial polymerization of derivatized multifunctional prepolymers

    DOEpatents

    Lonsdale, Harold K.; Wamser, Carl C.

    1988-01-01

    The preparation of a novel class of thin film membranes by interfacial polymerization is disclosed, said membanes incorporating as part of their polymeric structure the functionality of monomeric or oligomeric precursors. Specific embodiments include porphyrin and phthalocyanime derivatives that are photochemically or electrochemically active, as well as chemically asymmetric membranes.

  18. Ultrasound aided photochemical synthesis of Ag loaded TiO2 nanotube arrays to enhance photocatalytic activity.

    PubMed

    Sun, Lan; Li, Jing; Wang, Chenglin; Li, Sifang; Lai, Yuekun; Chen, Hongbo; Lin, Changjian

    2009-11-15

    This work presents a novel approach for preparing TiO(2) nanotube array photocatalyst loaded with highly dispersed Ag nanoparticles through an ultrasound aided photochemical route. The Ag content loaded on the array was controlled by changing the concentration of AgNO(3) solution. The Ag-TiO(2) nanotube arrays were characterized by SEM, XRD, XPS and UV-vis absorption. The effects of Ag content on the photoelectrochemical (PEC) property and photocatalytic activity of TiO(2) nanotube array electrode were studied. The results showed that Ag loading significantly enhanced the photocurrent and photocatalytic degradation rate of TiO(2) nanotube array under UV-light irradiation. The photocurrent and photocatalytic degradation rate of Ag-TiO(2) nanotube array prepared in 0.006 M AgNO(3) solution were about 1.2 and 3.7 times as that of pure TiO(2) nanotube array, respectively.

  19. Cellular Delivery and Photochemical Activation of Antisense Agents through a Nucleobase Caging Strategy

    PubMed Central

    Govan, Jeane M.; Uprety, Rajendra; Thomas, Meryl; Lusic, Hrvoje; Lively, Mark O.; Deiters, Alexander

    2013-01-01

    Antisense oligonucleotides are powerful tools to regulate gene expression in cells and model organisms. However, a transfection or microinjection is needed for efficient delivery of the antisense agent. We report the conjugation of multiple HIV TAT peptides to a hairpin-protected antisense agent through a light-cleavable nucleobase caging group. This conjugation allows for the facile delivery of the antisense agent without a transfection reagent and photochemical activation offers precise control over gene expression. The developed approach is highly modular, as demonstrated by the conjugation of folic acid to the caged antisense agent. This enabled targeted cell delivery through cell-surface folate receptors followed by photochemical triggering of antisense activity. Importantly, the presented strategy delivers native oligonucleotides after light-activation, devoid of any delivery functionalities or modifications that could otherwise impair their antisense activity. PMID:23915424

  20. Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods.

    PubMed

    Kalisman, Philip; Nakibli, Yifat; Amirav, Lilac

    2016-02-11

    We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

  1. H2S mediated thermal and photochemical methane activation

    PubMed Central

    Baltrusaitis, Jonas; de Graaf, Coen; Broer, Ria; Patterson, Eric

    2013-01-01

    Sustainable, low temperature methods of natural gas activation are critical in addressing current and foreseeable energy and hydrocarbon feedstock needs. Large portions of natural gas resources are still too expensive to process due to their high content of hydrogen sulfide gas (H2S) in mixture with methane, CH4, altogether deemed as sub-quality or “sour” gas. We propose a unique method for activating this “sour” gas to form a mixture of sulfur-containing hydrocarbon intermediates, CH3SH and CH3SCH3, and an energy carrier, such as H2. For this purpose, we computationally investigated H2S mediated methane activation to form a reactive CH3SH species via direct photolysis of sub-quality natural gas. Photoexcitation of hydrogen sulfide in the CH4+H2S complex results in a barrier-less relaxation via a conical intersection to form a ground state CH3SH+H2 complex. The resulting CH3SH can further be heterogeneously coupled over acidic catalysts to form higher hydrocarbons while the H2 can be used as a fuel. This process is very different from a conventional thermal or radical-based processes and can be driven photolytically at low temperatures, with enhanced controllability over the process conditions currently used in industrial oxidative natural gas activation. Finally, the proposed process is CO2 neutral, as opposed to the currently industrially used methane steam reforming (SMR). PMID:24150813

  2. H2S-mediated thermal and photochemical methane activation.

    PubMed

    Baltrusaitis, Jonas; de Graaf, Coen; Broer, Ria; Patterson, Eric V

    2013-12-02

    Sustainable, low-temperature methods for natural gas activation are critical in addressing current and foreseeable energy and hydrocarbon feedstock needs. Large portions of natural gas resources are still too expensive to process due to their high content of hydrogen sulfide gas (H2S) mixed with methane, deemed altogether as sub-quality or "sour" gas. We propose a unique method of activation to form a mixture of sulfur-containing hydrocarbon intermediates, CH3SH and CH3SCH3 , and an energy carrier such as H2. For this purpose, we investigated the H2S-mediated methane activation to form a reactive CH3SH species by means of direct photolysis of sub-quality natural gas. Photoexcitation of hydrogen sulfide in the CH4 + H2S complex resulted in a barrierless relaxation by a conical intersection to form a ground-state CH3SH + H2 complex. The resulting CH3SH could further be coupled over acidic catalysts to form higher hydrocarbons, and the resulting H2 used as a fuel. This process is very different from conventional thermal or radical-based processes and can be driven photolytically at low temperatures, with enhanced control over the conditions currently used in industrial oxidative natural gas activation. Finally, the proposed process is CO2 neutral, as opposed to the current industrial steam methane reforming (SMR).

  3. Photochemical arrays formed by spatial compartmentalization of colloidal nanoparticles in a polymer-based hydrogel

    SciTech Connect

    Firestone, M. A.; Rajh, T.; Makarova, O. V.; Seifert, S.; Tiede, D. M.; Thurnauer, M. C.

    2000-01-13

    The development of practical strategies for the assembly of semiconductor and metal colloid nanoparticles into ordered architectures is an area of considerable current interest, since it offers an opportunity for exploiting the optical and electronic properties of these colloids for device development. Prior research has explored creating such organized nanoparticle assemblies by Langmuir-Blodgett techniques or controlled solvent evaporation on suitable substrates. These approaches suffer from several limitations, however, most notably the generation of relatively simple structures and the lack of structural tailorability, preventing full exploitation of these materials. More recently, directed assembly using chemisorption of streptavidin-biotin or thiol-derivatized gold nanoparticles onto substrates has been described. Alternative approaches to achieving two-dimensional confinement of nanoparticles that do not involve substrate-supported materials, but rather organize the nanoparticles into mesoscopically-ordered soft condensed matter, may offer the advantage of enhanced processability and may permit construction of nanocomposite structures based on functional nanoparticles embedded in a processable, polymer-based matrix. This work describes the development of an alternative strategy for constructing 2-D arrays of functional metal and semiconductor nanoparticles. The approach involves directing the organization of nanocrystals into a processable (i.e., by externally applied magnetic and electric fields) polymer-grafted lipid-based complex fluid. By altering the surface chemistry of the nanoparticles, they can be selectively placed into defined regions encapsulating matrix.

  4. Optically controlled interparticle distance tuning and welding of single gold nanoparticle pairs by photochemical metal deposition.

    PubMed

    Härtling, T; Alaverdyan, Y; Hille, A; Wenzel, M T; Käll, M; Eng, L M

    2008-08-04

    We report on the in-situ controlled tuning of the particle gap in single pairs of gold nanodisks by photochemical metal deposition. The optically induced growth of nanodisk dimers fabricated by electron beam lithography leads to a decrease of the interparticle gap width down to 0 nm. Due to the increasing particle size and stronger plasmonic coupling, a smooth redshift of the localized surface plasmon (LSP) resonances is observed in such particle pairs during the growth process. The interparticle gap width, and hence the LSP resonance, can be tuned to any desired spectral position. The experimental results we obtain with this nanoscale fabrication technique are well described by the so-called plasmon ruler equation. Consequently, both the changes in particle diameter as well as in gap width can be characterized in-situ via far-field read-out of the optical properties of the dimers.

  5. Nanoparticles under the light: click functionalization by photochemical thiol-yne reaction, towards double click functionalization.

    PubMed

    Demay-Drouhard, Paul; Nehlig, Emilie; Hardouin, Julie; Motte, Laurence; Guénin, Erwann

    2013-06-24

    A light click away: The first application of the thiol-yne reaction to nanoparticle functionalization is described (see figure). This metal-free click chemistry approach is compatible with the addition of various molecules at the surface and can be combined with CuAAC methodology to perform chemoselective double functionalization.

  6. Light-induced hysteresis and recovery behaviors in photochemically activated solution-processed metal-oxide thin-film transistors

    SciTech Connect

    Jo, Jeong-Wan; Park, Sung Kyu E-mail: skpark@cau.ac.kr; Kim, Yong-Hoon E-mail: skpark@cau.ac.kr

    2014-07-28

    In this report, photo-induced hysteresis, threshold voltage (V{sub T}) shift, and recovery behaviors in photochemically activated solution-processed indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) are investigated. It was observed that a white light illumination caused negative V{sub T} shift along with creation of clockwise hysteresis in electrical characteristics which can be attributed to photo-generated doubly ionized oxygen vacancies at the semiconductor/gate dielectric interface. More importantly, the photochemically activated IGZO TFTs showed much reduced overall V{sub T} shift compared to thermally annealed TFTs. Reduced number of donor-like interface states creation under light illumination and more facile neutralization of ionized oxygen vacancies by electron capture under positive gate potential are claimed to be the origin of the less V{sub T} shift in photochemically activated TFTs.

  7. Selective photochemical synthesis of Ag nanoparticles on position-controlled ZnO nanorods for the enhancement of yellow-green light emission.

    PubMed

    Park, Hyeong-Ho; Zhang, Xin; Lee, Keun Woo; Sohn, Ahrum; Kim, Dong-Wook; Kim, Joondong; Song, Jin-Won; Choi, Young Su; Lee, Hee Kwan; Jung, Sang Hyun; Lee, In-Geun; Cho, Young-Dae; Shin, Hyun-Beom; Sung, Ho Kun; Park, Kyung Ho; Kang, Ho Kwan; Park, Won-Kyu; Park, Hyung-Ho

    2015-12-28

    A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to preferentially form Ag NPs on ZnO nanorods. The ratio of visible emission to ultraviolet (UV) emission for the Ag NP-decorated ZnO nanorod arrays, synthesized for 30 min, is 20.5 times that for the ZnO nanorod arrays without Ag NPs. The enhancement of the visible emission is believed to associate with the surface plasmon (SP) effect of Ag NPs. The Ag NP-decorated ZnO nanorod arrays show significant SP-induced enhancement of yellow-green light emission, which could be useful in optoelectronic applications. The technique developed here requires low processing temperatures (120 °C and lower) and no high-vacuum deposition tools, suitable for applications such as flexible electronics.

  8. Controlled preparation of Au/Ag/SnO2 core-shell nanoparticles using a photochemical method and applications in LSPR based sensing.

    PubMed

    Zhou, Na; Ye, Chen; Polavarapu, Lakshminarayana; Xu, Qing-Hua

    2015-05-21

    A photochemical method for the controlled preparation of core-shell Au/Ag/SnO2 nanorods (NRs) and nanospheres (NSs) has been developed based on photo-induced electron transfer processes in the plasmonic metal-semiconductor system. Au/AgNR/SnO2 and Au/AgNS/SnO2 were prepared by the UV irradiation of a mixture of mesoporous SnO2 coated AuNRs, or AuNSs, and AgNO3, in which AgNO3 was reduced by electrons transferred from the photo-excited mesoporous SnO2 (semiconductor) to the gold (metal). This method allows precise control over the composition and optical properties of the obtained nanoparticles. The LSPR refractive index sensitivity of the obtained Au/AgNR/SnO2 nanoparticles has been optimized to obtain a refractive index sensitivity of ∼442 nm RIU(-1). The optimized nanoparticles were subsequently chosen for the LSPR based sensing of glutathione (GSH) with the limit of detection of ∼7.5 × 10(-7) M. This photochemical method allows the controlled preparation of various Au/Ag/SnO2 nanoparticles to adjust their LSPR to suit various applications.

  9. Fabrication of two-dimensional Au at FePt core-shell nanoparticle arrays by photochemical metal deposition

    SciTech Connect

    Haertling, Thomas; Uhlig, Tino; Olk, Phillip; Eng, Lukas M.; Seidenstuecker, Axel; Wiedwald, Ulf; Han Luyang; Plettl, Alfred; Ziemann, Paul; Bigall, Nadja C.; Eychmueller, Alexander

    2010-05-03

    In this report, we experimentally demonstrate that single platinum nanoparticles exhibit the necessary catalytic activity for the optically induced reduction of H[AuCl{sub 4}] complexes to elemental gold. This finding is exploited for the parallel Au encapsulation of FePt nanoparticles arranged in a self-assembled two-dimensional array. Magnetic force microscopy reveals that the thin gold layer formed on the FePt particles leads to a strongly increased long-term stability of their magnetization under ambient conditions.

  10. Dinitrogen reduction via photochemical activation of heteroleptic tris(cyclopentadienyl) rare-earth complexes.

    PubMed

    Fieser, Megan E; Bates, Jefferson E; Ziller, Joseph W; Furche, Filipp; Evans, William J

    2013-03-13

    Dinitrogen can be reduced by photochemical activation of the Ln(3+) mixed-ligand tris(cyclopentadienyl) rare-earth complexes (η(5)-C5Me5)(3-x)(C5Me4H)(x)Ln (Ln = Y, Lu, Dy; x = 1, 2). [(C5Me4R)2Ln]2(μ-η(2):η(2)-N2) products (R = H, Me) are formed in reactions in which N2 is reduced to (N═N)(2-) and (C5Me4H)(-) is oxidized to (C5Me4H)2. Density functional theory indicates that this unusual example of rare-earth photochemistry can be rationalized by absorptions involving the (η(3)-C5Me4H)(-) ligands.

  11. In Situ Photochemical Activation of Sulfate for Enhanced Degradation of Organic Pollutants in Water.

    PubMed

    Liu, Guoshuai; You, Shijie; Tan, Yang; Ren, Nanqi

    2017-02-21

    The advanced oxidation process (AOP) based on SO4(•-) radicals has been receiving growing attention in water and wastewater treatment. Producing SO4(•-) radicals by activation of peroxymonosulfate or persulfate faces the challenges of high operational cost and potential secondary pollution. In this study, we report the in situ photochemical activation of sulfate (i-PCAS) to produce SO4(•-) radicals with bismuth phosphate (BPO) serving as photocatalyst. The prepared BPO rod-like material could achieve remarkably enhanced degradation of 2,4-dichlorophenol (2,4-DCP) in the presence of sulfate, indicated by the first-order kinetic constant (k = 0.0402 min(-1)) being approximately 2.1 times that in the absence (k = 0.019 min(-1)) at pH-neutral condition. This presented a marked contrast with commercial TiO2 (P25), the performance of which was always inhibited by sulfate. The impact of radical scavenger and electrolyte, combined with electron spin resonance (ESR) measurement, verified the formation of •OH and SO4(•-) radicals during i-PCAS process. According to theoretical calculations, BPO has a sufficiently high valence band potential making it thermodynamically favorable for sulfate oxidation, and weaker interaction with SO4(•-) radicals resulting in higher reactivity toward target organic pollutant. The concept of i-PCAS appears to be attractive for creating new photochemical systems where in situ production of SO4(•-) radicals can be realized by using sulfate originally existing in aqueous environment. This eliminates the need for extrinsic chemicals and pH adjustment, which makes water treatment much easier, more economical, and more sustainable.

  12. Photochemical activation increases the porcine corneal stiffness and resistance to collagenase digestion.

    PubMed

    Wang, Ti; Peng, Yinbo; Shen, Nianci; Yu, Yan; Yao, Min; Zhu, Jingyin

    2014-06-01

    In this study, we explore the effect of photochemical activation induced corneal cross-linking, utilizing Rose Bengal (RB) and 532 nm green light irradiation (RB-PCL), on porcine corneal biomechanical rigidity and the biochemical resistance against collagenase digestion. A protocol with a wavelength of 532 nm and illumination intensity of 0.4W/cm(2) for 250 s to deliver a dose of 100 J/cm(2) was chosen. Using confocal microscopy, we demonstrated that the diffusion depth of RB into porcine cornea was approximately 150 μm and mostly localized in anterior stroma 25 min followed by RB application. After photochemical cross-linking, an increase in tensile strength (by average 200%) and Young's modulus (by average 200%) in porcine corneas was observed. The corneal buttons treated by RB-PCL showed doubling of collagenase digestion time from 10.8 ± 3.1 days in the blank group to 19.7 ± 6.2 days in the RB-PCL group, indicating increased resistance to enzymatic digestion. In conclusion, Collagen cross-linking by RB-PCL increased both the biomechanical stiffness and the biochemical resistance against collagenase digestion in porcine corneas, therefore to allow stabilizing and solidifier the cornea. The advantages and disadvantages of RB-PCL versus UVA/riboflavin cross-linking technique (UV-CXL) are fully explored. Due to the nature of minimal penetration of RB into corneal stroma, the RB-PCL method could potentially be used in patients with corneal thickness less than 400 μm where UV-CXL is limited.

  13. [Effects of exogenous nitric oxide on highbush blueberry PSII photochemical activity and antioxidant system under high temperature stress].

    PubMed

    Wei, Hai-rong; Meng, Yan-ling; Sun, Yang; Liu, Qing-zhong

    2010-10-01

    Taking the test tube 'Duke' highbush blueberry (Vaccinium corymbosum) seedlings having been transplanted to the field for 6 months as test materials, this paper studied the effects of exogenous nitric oxide (NO) on their growth, PS II photochemical activity, and antioxidant system under high temperature stress. Applying 0.2, 0.5, and 1.0 mmol x L(-1) of exogenous sodium nitroprusside (SNP) could alleviate the decrease of maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency under light (phi PS II), photochemical quench (q(P)), and nonphotochemical quench (NPQ) caused by high temperature, and prevented the damage of high temperature on photosynthetic apparatus. Comparing with the control, treatments NO decreased the leaf membrane permeability and MDA content, increased the SOD and CAT activities significantly, and promoted proline accumulation. Appropriate concentration SNP could significantly alleviate the damage of high temperature stress on highbush blueberry seedlings, and 0.5 mmol x L(-1) of SNP had the most satisfactory effect.

  14. The photochemical reflectance index provides an optical indicator of spring photosynthetic activation in evergreen conifers.

    PubMed

    Wong, Christopher Y S; Gamon, John A

    2015-04-01

    In evergreens, the seasonal down-regulation and reactivation of photosynthesis is largely invisible and difficult to assess with remote sensing. This invisible phenology may be changing as a result of climate change. To better understand the mechanism and timing of these hidden physiological transitions, we explored several assays and optical indicators of spring photosynthetic activation in conifers exposed to a boreal climate. The photochemical reflectance index (PRI), chlorophyll fluorescence, and leaf pigments for evergreen conifer seedlings were monitored over 1 yr of a boreal climate with the addition of gas exchange during the spring. PRI, electron transport rate, pigment levels, light-use efficiency and photosynthesis all exhibited striking seasonal changes, with varying kinetics and strengths of correlation, which were used to evaluate the mechanisms and timing of spring activation. PRI and pigment pools were closely timed with photosynthetic reactivation measured by gas exchange. The PRI provided a clear optical indicator of spring photosynthetic activation that was detectable at leaf and stand scales in conifers. We propose that PRI might provide a useful metric of effective growing season length amenable to remote sensing and could improve remote-sensing-driven models of carbon uptake in evergreen ecosystems.

  15. Selective photochemical synthesis of Ag nanoparticles on position-controlled ZnO nanorods for the enhancement of yellow-green light emission

    NASA Astrophysics Data System (ADS)

    Park, Hyeong-Ho; Zhang, Xin; Lee, Keun Woo; Sohn, Ahrum; Kim, Dong-Wook; Kim, Joondong; Song, Jin-Won; Choi, Young Su; Lee, Hee Kwan; Jung, Sang Hyun; Lee, In-Geun; Cho, Young-Dae; Shin, Hyun-Beom; Sung, Ho Kun; Park, Kyung Ho; Kang, Ho Kwan; Park, Won-Kyu; Park, Hyung-Ho

    2015-12-01

    A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to preferentially form Ag NPs on ZnO nanorods. The ratio of visible emission to ultraviolet (UV) emission for the Ag NP-decorated ZnO nanorod arrays, synthesized for 30 min, is 20.5 times that for the ZnO nanorod arrays without Ag NPs. The enhancement of the visible emission is believed to associate with the surface plasmon (SP) effect of Ag NPs. The Ag NP-decorated ZnO nanorod arrays show significant SP-induced enhancement of yellow-green light emission, which could be useful in optoelectronic applications. The technique developed here requires low processing temperatures (120 °C and lower) and no high-vacuum deposition tools, suitable for applications such as flexible electronics.A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to

  16. Antimicrobial Activity of Commercial Nanoparticles

    NASA Astrophysics Data System (ADS)

    Gajjar, Priyanka; Pettee, Brian; Britt, David W.; Huang, Wenjie; Johnson, William P.; Anderson, Anne J.

    2009-07-01

    Engineered nanoparticles are finding increased use in applications ranging from biosensors to prophylactic antimicrobials embedded in socks. The release of heavy metal-containing nanoparticles (NP) into the environment may be harmful to the efficacy of beneficial microbes that function in element cycling, pollutant degradation, and plant growth. Antimicrobial activity of commercial NP of Ag, CuO, and ZnO is demonstrated here against the beneficial soil microbe, Pseudomonas putida KT2440, which was modified to serve as a bioluminescent sentinel organism. "As manufactured" preparations of nano- Ag, -CuO, and -ZnO caused rapid, dose dependent loss of light output in the biosensor. Bulk equivalents of these products showed no inhibitory activity, indicating that particle size was determinant in activity.

  17. Controlled preparation of Au/Ag/SnO2 core-shell nanoparticles using a photochemical method and applications in LSPR based sensing

    NASA Astrophysics Data System (ADS)

    Zhou, Na; Ye, Chen; Polavarapu, Lakshminarayana; Xu, Qing-Hua

    2015-05-01

    A photochemical method for the controlled preparation of core-shell Au/Ag/SnO2 nanorods (NRs) and nanospheres (NSs) has been developed based on photo-induced electron transfer processes in the plasmonic metal-semiconductor system. Au/AgNR/SnO2 and Au/AgNS/SnO2 were prepared by the UV irradiation of a mixture of mesoporous SnO2 coated AuNRs, or AuNSs, and AgNO3, in which AgNO3 was reduced by electrons transferred from the photo-excited mesoporous SnO2 (semiconductor) to the gold (metal). This method allows precise control over the composition and optical properties of the obtained nanoparticles. The LSPR refractive index sensitivity of the obtained Au/AgNR/SnO2 nanoparticles has been optimized to obtain a refractive index sensitivity of ~442 nm RIU-1. The optimized nanoparticles were subsequently chosen for the LSPR based sensing of glutathione (GSH) with the limit of detection of ~7.5 × 10-7 M. This photochemical method allows the controlled preparation of various Au/Ag/SnO2 nanoparticles to adjust their LSPR to suit various applications.A photochemical method for the controlled preparation of core-shell Au/Ag/SnO2 nanorods (NRs) and nanospheres (NSs) has been developed based on photo-induced electron transfer processes in the plasmonic metal-semiconductor system. Au/AgNR/SnO2 and Au/AgNS/SnO2 were prepared by the UV irradiation of a mixture of mesoporous SnO2 coated AuNRs, or AuNSs, and AgNO3, in which AgNO3 was reduced by electrons transferred from the photo-excited mesoporous SnO2 (semiconductor) to the gold (metal). This method allows precise control over the composition and optical properties of the obtained nanoparticles. The LSPR refractive index sensitivity of the obtained Au/AgNR/SnO2 nanoparticles has been optimized to obtain a refractive index sensitivity of ~442 nm RIU-1. The optimized nanoparticles were subsequently chosen for the LSPR based sensing of glutathione (GSH) with the limit of detection of ~7.5 × 10-7 M. This photochemical method allows

  18. Mycosynthesis of silver nanoparticles bearing antibacterial activity

    PubMed Central

    Azmath, Pasha; Baker, Syed; Rakshith, Devaraju; Satish, Sreedharamurthy

    2015-01-01

    Mycosynthesis of silver nanoparticles was achieved by endophytic Colletotrichum sp. ALF2-6 inhabiting Andrographis paniculata. Well dispersed nanoparticles were characterized using UV–Visible spectrometry with maximum absorption conferring at 420 nm. FTIR analysis revealed possible biomolecules reducing the metal salt and stabilization of nanoparticles. XRD analysis depicted the diffraction intensities exhibiting between 20 and 80 °C at 2theta angle thus conferring the crystalline nature of nanoparticles. Morphological characteristic using TEM revealed the polydispersity of nanoparticles with size ranging from 20 to 50 nm. Synthesized nanoparticles exhibited bactericidal activity against selected human pathogens. Nanoparticles mode of action was carried out to reveal DNA damage activity. Thus the present investigation reports facile fabrication of silver nanoparticles from endophytic fungi. PMID:27013906

  19. Brassica rapa plants adapted to microgravity with reduced photosystem I and its photochemical activity

    NASA Technical Reports Server (NTRS)

    Jiao, Shunxing; Hilaire, Emmanuel; Paulsen, Avelina Q.; Guikema, James A.

    2004-01-01

    The photosynthetic apparatus contains several protein complexes, many of which are regulated by environmental conditions. In this study, the influences of microgravity on PSI and PSII in Brassica rapa plants grown aboard the space shuttle were examined. We found that Brassica plants grown in space had a normal level of growth relative to controls under similar conditions on Earth. Upon return to Earth, cotyledons were harvested and thylakoid membranes were isolated. Analysis of chlorophyll contents showed that the Chl a/b ratio (3.5) in flight cotyledons was much higher than a ratio of 2.42 in the ground controls. The flight samples also had a reduction of PSI complexes and a corresponding 30% decrease of PSI photochemical activity. Immunoblotting showed that the reaction centre polypeptides of PSI were more apparently decreased (e.g. by 24-33% for PsaA and PsaB, and 57% for PsaC) than the light-harvesting complexes. In comparison, the accumulation of PSII complex was less affected in microgravity, thus only a slight reduction in D1, D2 and LHCII was observed in protein blots. However, there was a 32% decrease of OEC1 in the flight samples, indicating a defective OEC subcomplex. In addition, an average 54% increase of the 54 kDa CF1-beta isoform was found in the flight samples, suggesting that space-grown plants suffered from certain stresses, consistent with implications of the increased Chl a/b ratio. Taken together, the results demonstrated that Brassica plants can adapt to spaceflight microgravity, but with significant alterations in chloroplast structures and photosynthetic complexes, and especially reduction of PSI and its activity.

  20. A photochemical activation scheme of inert dinitrogen by dinuclear Ru(II) and Fe(II) complexes.

    PubMed

    Reiher, Markus; Kirchner, Barbara; Hutter, Jürg; Sellmann, Dieter; Hess, Bernd Artur

    2004-09-20

    A general photochemical activation process of inert dinitrogen coordinated to two metal centers is presented on the basis of high-level DFT and ab initio calculations. The central feature of this activation process is the occupation of an antibonding pi* orbital upon electronic excitation from the singlet ground state S0 to the first excited singlet state S1. Populating the antibonding LUMO weakens the triple bond of dinitrogen. After a vertical excitation, the excited complex may structurally relax in the S1 state and approaches its minimum structure in the S1 state. This excited-state minimum structure features the dinitrogen bound in a diazenoid form, which exhibits a double bond and two lone pairs localized at the two nitrogen atoms, ready to be protonated. Reduction and de-excitation then yield the corresponding diazene complex; its generation represents the essential step in a nitrogen fixation and reduction protocol. The consecutive process of excitation, protonation, and reduction may be rearranged in any experimentally appropriate order. The protons needed for the reaction from dinitrogen to diazene can be provided by the ligand sphere of the complexes, which contains sulfur atoms acting as proton acceptors. These protonated thiolate functionalities bring protons close to the dinitrogen moiety. Because protonation does not change the pi*-antibonding character of the LUMO, the universal and well-directed character of the photochemical activation process makes it possible to protonate the dinitrogen complex before it is irradiated. The pi*-antibonding LUMO plays the central role in the activation process, since the diazenoid structure was obtained by excitation from various occupied orbitals as well as by a direct two-electron reduction (without photochemical activation) of the complex; that is, the important bending of N2 towards a diazenoid conformation can be achieved by populating the pi*-antibonding LUMO.

  1. Flexible metal-oxide devices made by room-temperature photochemical activation of sol-gel films.

    PubMed

    Kim, Yong-Hoon; Heo, Jae-Sang; Kim, Tae-Hyeong; Park, Sungjun; Yoon, Myung-Han; Kim, Jiwan; Oh, Min Suk; Yi, Gi-Ra; Noh, Yong-Young; Park, Sung Kyu

    2012-09-06

    Amorphous metal-oxide semiconductors have emerged as potential replacements for organic and silicon materials in thin-film electronics. The high carrier mobility in the amorphous state, and excellent large-area uniformity, have extended their applications to active-matrix electronics, including displays, sensor arrays and X-ray detectors. Moreover, their solution processability and optical transparency have opened new horizons for low-cost printable and transparent electronics on plastic substrates. But metal-oxide formation by the sol-gel route requires an annealing step at relatively high temperature, which has prevented the incorporation of these materials with the polymer substrates used in high-performance flexible electronics. Here we report a general method for forming high-performance and operationally stable metal-oxide semiconductors at room temperature, by deep-ultraviolet photochemical activation of sol-gel films. Deep-ultraviolet irradiation induces efficient condensation and densification of oxide semiconducting films by photochemical activation at low temperature. This photochemical activation is applicable to numerous metal-oxide semiconductors, and the performance (in terms of transistor mobility and operational stability) of thin-film transistors fabricated by this route compares favourably with that of thin-film transistors based on thermally annealed materials. The field-effect mobilities of the photo-activated metal-oxide semiconductors are as high as 14 and 7 cm(2) V(-1) s(-1) (with an Al(2)O(3) gate insulator) on glass and polymer substrates, respectively; and seven-stage ring oscillators fabricated on polymer substrates operate with an oscillation frequency of more than 340 kHz, corresponding to a propagation delay of less than 210 nanoseconds per stage.

  2. Mechanism of the Stereoselective α-Alkylation of Aldehydes Driven by the Photochemical Activity of Enamines

    PubMed Central

    2016-01-01

    Herein we describe our efforts to elucidate the key mechanistic aspects of the previously reported enantioselective photochemical α-alkylation of aldehydes with electron-poor organic halides. The chemistry exploits the potential of chiral enamines, key organocatalytic intermediates in thermal asymmetric processes, to directly participate in the photoexcitation of substrates either by forming a photoactive electron donor–acceptor complex or by directly reaching an electronically excited state upon light absorption. These photochemical mechanisms generate radicals from closed-shell precursors under mild conditions. At the same time, the ground-state chiral enamines provide effective stereochemical control over the enantioselective radical-trapping process. We use a combination of conventional photophysical investigations, nuclear magnetic resonance spectroscopy, and kinetic studies to gain a better understanding of the factors governing these enantioselective photochemical catalytic processes. Measurements of the quantum yield reveal that a radical chain mechanism is operative, while reaction-profile analysis and rate-order assessment indicate the trapping of the carbon-centered radical by the enamine, to form the carbon–carbon bond, as rate-determining. Our kinetic studies unveil the existence of a delicate interplay between the light-triggered initiation step and the radical chain propagation manifold, both mediated by the chiral enamines. PMID:27267587

  3. Antitumor Activities of Metal Oxide Nanoparticles

    PubMed Central

    Vinardell, Maria Pilar; Mitjans, Montserrat

    2015-01-01

    Nanoparticles have received much attention recently due to their use in cancer therapy. Studies have shown that different metal oxide nanoparticles induce cytotoxicity in cancer cells, but not in normal cells. In some cases, such anticancer activity has been demonstrated to hold for the nanoparticle alone or in combination with different therapies, such as photocatalytic therapy or some anticancer drugs. Zinc oxide nanoparticles have been shown to have this activity alone or when loaded with an anticancer drug, such as doxorubicin. Other nanoparticles that show cytotoxic effects on cancer cells include cobalt oxide, iron oxide and copper oxide. The antitumor mechanism could work through the generation of reactive oxygen species or apoptosis and necrosis, among other possibilities. Here, we review the most significant antitumor results obtained with different metal oxide nanoparticles.

  4. Recyclable decoration of amine-functionalized magnetic nanoparticles with Ni(2+) for determination of histidine by photochemical vapor generation atomic spectrometry.

    PubMed

    Hu, Yuan; Wang, Qi; Zheng, Chengbin; Wu, Li; Hou, Xiandeng; Lv, Yi

    2014-01-07

    It is critically important to accurately determine histidine since it is an indicator for many diseases when at an abnormal level. Here, an inexpensive and simple method using an amine-functionalized magnetic nanoparticle-based Ni(2+)-histidine affinity pair system was developed for highly sensitive and selective detection of histidine in human urine by photochemical vapor generation atomic spectrometry. Ni(2+) was first bound to the amine groups of the amine-functionalized magnetic nanoparticles and then liberated to solution via the highly specific interaction between the histidine and Ni(2+) in the presence of histidine. The liberated histidine-Ni(2+) complex was exposed to UV irradiation in the presence of formic acid to form gaseous nickel tetracarbonyl, which was separated from the sample matrix and determined by atomic absorption/fluorescence spectrometry. Compared to other methods, this approach promises high sensitivity, simplicity in design, and convenient operation. The need for organic solvents, enzymatic reactions, separation processes, chemical modification, expensive instrumentations, and sophisticated and complicated pretreatment is minimized with this strategy. A limit of detection of 1 nM was obtained and provided tens-to-hundreds of fold improvements over that achieved with conventional methods. The protocol was evaluated by analysis of several urine samples with good recoveries and showed great potential for practical application.

  5. Atmospheric carbon dioxide changes photochemical activity, soluble sugars and volatile levels in broccoli (Brassica oleracea var. italica).

    PubMed

    Krumbein, Angelika; Kläring, Hans-Peter; Schonhof, Ilona; Schreiner, Monika

    2010-03-24

    Atmospheric carbon dioxide (CO(2)) concentration is an environmental factor currently undergoing dramatic changes. The objective of the present study was to determine the effect of doubling the ambient CO(2) concentration on plant photochemistry as measured by photochemical quenching coefficient (qP), soluble sugars and volatiles in broccoli. Elevated CO(2) concentration increased qP values in leaves by up to 100% and 89% in heads, while glucose and sucrose in leaves increased by about 60%. Furthermore, in broccoli heads elevated CO(2) concentration induced approximately a 2-fold increase in concentrations of three fatty acid-derived C(7) aldehydes ((E)-2-heptenal, (E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal), two fatty acid-derived C(5) alcohols (1-penten-3-ol, (Z)-2-pentenol), and two amino acid-derived nitriles (phenyl propanenitrile, 3-methyl butanenitrile). In contrast, concentrations of the sulfur-containing compound 2-ethylthiophene and C(6) alcohol (E)-2-hexenol decreased. Finally, elevated CO(2) concentration increased soluble sugar concentrations due to enhanced photochemical activity in leaves and heads, which may account for the increased synthesis of volatiles.

  6. Photochemical and Photophysical Properties of Phthalocyanines Modified with Optically Active Alcohols.

    PubMed

    Ramos, Aline A; Nascimento, Francisco B; de Souza, Thaiza F M; Omori, Alvaro T; Manieri, Tânia M; Cerchiaro, Giselle; Ribeiro, Anderson O

    2015-07-24

    Three phthalocyanine derivatives were synthesized and characterized: one modified with a racemic mixture of 1-(4-bromophenyl)ethanol and two other macrocycles modified with each one of the enantioenriched isomers (R)-1-(4-bromophenyl)ethanol and (S)-1-(4-bromophenyl)ethanol. The compounds were characterized by 1H-NMR spectroscopy, mass spectrometry, UV-Vis absorption, and excitation and emission spectra. Additionally, partition coefficient values and the quantum yield of the generation of oxygen reactive species were determined. Interestingly, the phthalocyanine containing a (R)-1-(4-bromophenyl)ethoxy moiety showed higher quantum yield of reactive oxygen species generation than other compounds under the same conditions. In addition, the obtained fluorescence microscopy and cell viability results have shown that these phthalocyanines have different interactions with mammary MCF-7 cells. Therefore, our results indicate that the photochemical and biological properties of phthalocyanines with chiral ligands should be evaluated separately for each enantiomeric species.

  7. Surface-enhanced Raman scattering-active Au/TiO{sub 2} films prepared by electrochemical and photochemical methods

    SciTech Connect

    Yang, Kuang-Hsuan; Chang, Chia-Ming

    2013-02-15

    Graphical abstract: In the presence of TiO{sub 2} NPs before the ORCs the optimal wavelength of UV light resulting in the strongest SERS effect being 310 nm. Display Omitted Highlights: ► SERS-active Au/TiO{sub 2} prepared by electrochemical and photochemical methods. ► UV light of 310 nm is suitable for obtaining Au/TiO{sub 2} with strong SERS effect. ► Presence of TiO{sub 2} before ORCs is responsible for obtaining SERS-active Au/TiO{sub 2}. -- Abstract: In this work, we report a new strategy for the preparation of surface-enhanced Raman scattering (SERS)-active Au/TiO{sub 2}(P25) nanocomposites (NCs), using electrochemical and photochemical methods. First, Au substrates were subjected to electrochemical oxidation–reduction cycles (ORCs) in a deoxygenated aqueous solution containing 0.1 M HCl and 1 mM TiO{sub 2}. After the ORC treatment AuCl{sub 4}{sup −}-adsorbed TiO{sub 2} complexes were produced in the solution. These complex-containing substrates were then irradiated with UV light at 310 nm to synthesize Au/TiO{sub 2} NCs with strong SERS activities for probe molecules of rhodamine 6G (R6G) and conductive polymers of polypyrrole (PPy). Experimental results indicated that the wavelength of UV light and the presence of TiO{sub 2} before and after the ORC procedure during the preparation process both affected the resulting SERS activities.

  8. Modeling biological activities of nanoparticles.

    PubMed

    Epa, V Chandana; Burden, Frank R; Tassa, Carlos; Weissleder, Ralph; Shaw, Stanley; Winkler, David A

    2012-11-14

    Products are increasingly incorporating nanomaterials, but we have a poor understanding of their adverse effects. To assess risk, regulatory authorities need more experimental testing of nanoparticles. Computational models play a complementary role in allowing rapid prediction of potential toxicities of new and modified nanomaterials. We generated quantitative, predictive models of cellular uptake and apoptosis induced by nanoparticles for several cell types. We illustrate the potential of computational methods to make a contribution to nanosafety.

  9. Systems and methods for solar energy storage, transportation, and conversion utilizing photochemically active organometallic isomeric compounds and solid-state catalysts

    DOEpatents

    Vollhardt, K. Peter C.; Segalman, Rachel A; Majumdar, Arunava; Meier, Steven

    2015-02-10

    A system for converting solar energy to chemical energy, and, subsequently, to thermal energy includes a light-harvesting station, a storage station, and a thermal energy release station. The system may include additional stations for converting the released thermal energy to other energy forms, e.g., to electrical energy and mechanical work. At the light-harvesting station, a photochemically active first organometallic compound, e.g., a fulvalenyl diruthenium complex, is exposed to light and is photochemically converted to a second, higher-energy organometallic compound, which is then transported to a storage station. At the storage station, the high-energy organometallic compound is stored for a desired time and/or is transported to a desired location for thermal energy release. At the thermal energy release station, the high-energy organometallic compound is catalytically converted back to the photochemically active organometallic compound by an exothermic process, while the released thermal energy is captured for subsequent use.

  10. Solar photochemical oxidation of alcohols using catalytic hydroquinone and copper nanoparticles under oxygen: oxidative cleavage of lignin models.

    PubMed

    Mitchell, Lorna J; Moody, Christopher J

    2014-11-21

    Alcohols are converted into to their corresponding carbonyl compounds using catalytic amounts of 1,4-hydroquinone with a copper nanoparticle electron transfer mediator with oxygen as the terminal oxidant in acetone as solvent under visible light irradiation. These conditions employing biorenewable hydroquinone as reagent were developed from initial experiments using stoichiometric amounts of 1,4-benzoquinone as oxidant. A range of benzylic and aliphatic primary and secondary alcohols are oxidized, affording the corresponding aldehydes or ketones in moderate to excellent yields. The methodology is also applicable to the oxidative degradation of lignin model compounds that undergo C-C bond cleavage to give simple aromatic compounds.

  11. Photochemical internalization (PCI) enhanced nonviral transfection of tumor suppressor and pro-drug activating genes; a potential treatment modality for gliomas

    NASA Astrophysics Data System (ADS)

    Wang, Frederick; Zamora, Genesis; Sun, Chung-Ho; Trinidad, Anthony; Berg, Kristian; Madsen, Steen; Kwon, Young Jik; Hirschberg, Henry

    2014-03-01

    The overall objective of the research is to investigate the utility of photochemical internalization for the enhanced nonviral transfection of genes into cells. We have examined, in detail, the evaluation of photochemical internalization (PCI) as a method for the non-viral introduction of the tumor suppressor gene PTEN and the PCI mediated transfection of the cytosine deaminase (CD) pro drug activating gene into glioma cell monolayers and multi-cell tumor spheroids. Expression of the CD gene within the target cell produces an enzyme that converts the nontoxic prodrug, 5-fluorocytosine (5-FC), to the toxic metabolite, 5-fluorouracil (5-FU).

  12. Photochemical fine-tuning of luminescent color of cadmium selenide nanoparticles: fabricating a single-source multicolor luminophore.

    PubMed

    Torimoto, Tsukasa; Murakami, Shin-ya; Sakuraoka, Miwa; Iwasaki, Kentaro; Okazaki, Ken-ichi; Shibayama, Tamaki; Ohtani, Bunsho

    2006-07-13

    Size-selective photoetching was applied to silica-coated cadmium selenide (SiO2/CdSe) nanoparticles to precisely control their photoluminescence properties. The absorption spectra of CdSe was blue-shifted by irradiation of monochromatic light, and finally, the absorption onset agreed with the wavelength of irradiation light, indicating that CdSe particles were photoetched to smaller ones until the irradiated photons were not absorbed by the photoetched particles and that the SiO2 shell layer surrounding the CdSe core prevented coalescence between the photoetched particles. Although as-prepared SiO2/CdSe did not exhibit photoluminescence, the application of size-selective photoetching to SiO2/CdSe resulted in the development of the band gap emission, with the degree being enhanced with progress of the photoetching. The peak wavelength of photoluminescence decreased with a decrease in the wavelength used for the photoetching, so that the luminescence color could be tuned between red and blue. Partial photoetching of SiO2/CdSe nanoparticle films produced intense band gap emission of CdSe at the photoetched area, while the remainder of the SiO2/CdSe films did not exhibit detectable photoluminescence, resulting in the formation of a clear photoluminescence image under UV irradiation. This technique makes it possible to produce a multicolored photoluminescence image by irradiation with monochromatic lights having various wavelengths using a single source material.

  13. [Effects of high temperature on leaf photosynthetic characteristics and photosystem II photochemical activity of kernel-used apricot].

    PubMed

    Du, Guo-dong; Lü, De-guo; Zhao, Ling; Wang, Su-su; Cai, Qian

    2011-03-01

    In order to explore the photosynthetic adaption mechanisms of kernel-used apricot under high temperature stress, gas exchange technique and chlorophyll fluorescence transient technique (JIP-test) were adopted to study the leaf photosynthetic characteristics and photosystem II (PS II) photochemical activity of 4 year-old 'Chaoren' (Armeniaca vulgaris x sibirica) growing on Horqin sandy land at 25 degrees C, 30 degrees C, 40 degrees C, and 50 degrees C. Within a definite temperature range, and as the temperature increased, the 'Chaoren' could enhance its leaf photosynthetic pigments content and ratio to maintain the light absorption, transfer, and conversion, and thereby, to ensure the function of photosynthetic apparatus. However, when the temperature exceeded the physiological adjustment threshold of leaves, the chlorophyll began to be decomposed, net photosynthetic rate (Pn) declined obviously, and intercellular CO2 concentration (Ci) increased, indicating that the decline in photosynthesis was limited by mesophyll factor. At 40 degrees C, the density of PS II reaction centers per excited cross-section (RC/CS0) dropped distinctly; and at 50 degrees C, the K phase (Wk) and J phase (Vj) in the O-J-I-P chlorophyll fluorescence transients increased distinctly, indicating that high temperature damaged the oxygen-evolving complex (OEC), donor sides, and PS II reaction centers. In addition, the minimum chlorophyll fluorescence (F0) at 50 degrees C increased significantly by 1.26 times, compared with the control, and the maximum photochemical efficiency (Fv/Fm) and performance index (PI(ABS)) reduced to 37.9% and 10.3% of the control, respectively. High temperature injured the function of the donor and acceptor sides in the PS II of photosynthetic apparatus, leading to the decrease of photosynthetic efficiency, and being one of the main mechanisms for the damage of photosynthetic apparatus in kernel-used apricot leaves under high temperature stress.

  14. Photochemical Fabrication of Transition Metal Nanoparticles Using CdS Template and Their Co-Catalysis Effects for TiO2 Photocatalysis

    NASA Astrophysics Data System (ADS)

    Badhwar, Nidhi; Gupta, Nidhi; Pal, Bonamali

    2013-09-01

    Transition metal nanoparticles were prepared by chemical dissolution of CdS template from metal photodeposited CdS nanorod (length = 70-85 nm and width = 5-6 nm) heterocomposites. Size (9-10 nm) of metal nanoparticles obtained after CdS removal was larger than the size (4-6 nm) of metal nanodeposits over CdS template. The obtained Au nanoparticles displayed a broad red shifted absorption band at 660 nm, whereas Pt, Pd and Rh nanoparticles exhibit featureless absorption spectra. Elemental analysis confirms the complete removal of CdS template from Au-CdS (Au — 2.65 at.%) and Ag-CdS (Ag — 2.06 at.%) composites showing no Cd peak. These metal nanoparticles imparted dissimilar co-catalytic activity of TiO2 for photocatalytic degradation of salicylic acid in the order Au > Pt > Pd > Ag > Rh as a function of their nature, electronegativity, redox potential and work function.

  15. Preparation of photocatalytic ZnO nanoparticles and application in photochemical degradation of betamethasone sodium phosphate using taguchi approach

    NASA Astrophysics Data System (ADS)

    Giahi, M.; Farajpour, G.; Taghavi, H.; Shokri, S.

    2014-07-01

    In this study, ZnO nanoparticles were prepared by a sol-gel method for the first time. Taguchi method was used to identify the several factors that may affect degradation percentage of betamethasone sodium phosphate in wastewater in UV/K2S2O8/nano-ZnO system. Our experimental design consisted of testing five factors, i.e., dosage of K2S2O8, concentration of betamethasone sodium phosphate, amount of ZnO, irradiation time and initial pH. With four levels of each factor tested. It was found that, optimum parameters are irradiation time, 180 min; pH 9.0; betamethasone sodium phosphate, 30 mg/L; amount of ZnO, 13 mg; K2S2O8, 1 mM. The percentage contribution of each factor was determined by the analysis of variance (ANOVA). The results showed that irradiation time; pH; amount of ZnO; drug concentration and dosage of K2S2O8 contributed by 46.73, 28.56, 11.56, 6.70, and 6.44%, respectively. Finally, the kinetics process was studied and the photodegradation rate of betamethasone sodium phosphate was found to obey pseudo-first-order kinetics equation represented by the Langmuir-Hinshelwood model.

  16. Photochemical fabrication of size-controllable gold nanoparticles on chitosan and their application on catalytic decomposition of acetaldehyde

    SciTech Connect

    Yu, Chung-Chin; Yang, Kuang-Hsuan; Liu, Yu-Chuan; Chen, Bo-Chuen

    2010-07-15

    In this work, we report a new pathway to prepare size-controllable gold nanoparticles (NPs) on chitosan (Ch) in aqueous solutions for improving catalytic decomposition of acetaldehyde by pure gold NPs at room temperature. First, Au substrates were cycled in deoxygenated aqueous solutions containing 0.1N NaCl and 1 g/L Ch from -0.28 to +1.22 V vs Ag/AgCl at 500 mV/s for 200 scans. Then the solutions were irradiated with UV lights of different wavelengths to prepare size-controllable Au NPs on Ch. Experimental results indicate that the particle sizes of prepared NPs are increased when UV lights with longer wavelengths were employed. The particle sizes of resulted Au NPs can be controlled from 10 to 50 nm. Moreover, the decomposition of acetaldehydes in wines can be significantly enhanced by ca. 190% of magnitude due to the contribution of the adsorption of Au NPs on Ch.

  17. Photochemical degradation of an anionic surfactant by TiO2 nanoparticle doped with C, N in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zamiri, M.; Giahi, M.

    2016-12-01

    Novel C,N-doped TiO2 nanoparticles were prepared by a solid phase reaction. The catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The results showed that crystallite size of synthesized C,N-doped TiO2 particles were in nanoscale. UV light photocatalytic studies were carried out using sodium naphthalenesulfonate formaldehyde condensate (SNF) as a model pollutant. The effects of initial concentration of surfactant, catalyst amount, pH, addition of oxidant on the reaction rate were ascertained and optimum conditions for maximum degradation was determined. The results indicated that for a solution of 20 mg/L of SNF, almost 98.7% of the substance were removed at pH 4.0 and 0.44 g/L photocatalyst load, with addition of 1 mM K2S2O8 and irradiation time of 90 min. The kinetics of the process was studied, and the photodegradation rate of SNF was found to obey pseudo-first-order kinetics equation represented by the Langmuir-Hinshelwood model.

  18. Effect of cerium on photosynthetic pigments and photochemical reaction activity in soybean seedling under ultraviolet-B radiation stress.

    PubMed

    Liang, Chanjuan; Zhang, Guangsheng; Zhou, Qing

    2011-09-01

    Effects of cerium (Ce) on photosynthetic pigments and photochemical reaction activity in soybean (Glycine max L.) under ultraviolet-B (UV-B) radiation stress were studied under laboratory conditions. UV-B radiation caused the decrease in chlorophyll content, net photosynthetic rate, Hill reaction activity, photophosphorylation rate and Mg(2+)-ATPase activity. Ce (III) (20 mg L(-1)) could alleviate UV-B-induced inhibition to these photosynthetic parameters because values of these photosynthetic parameters in Ce (III) + UV-B treatment were obviously higher than those with UV-B treatment alone. Dynamic changes of the above photosynthetic parameters show that Ce (III) could slow down the decrease rate of these photosynthetic parameters during a 5-day UV-B radiation and quicken the restoration during recovery period. The final restoration degree of five parameters mentioned above in leaves exposed to low level of UV-B radiation (0.15 W m(2)) was higher than that exposed to high level (0.45 W m(2)). Correlating net photosynthetic rate with other four parameters, we found that the regulating mechanisms Ce (ΠΙ) on photosynthesis under various level of UV-B radiation were not the same. The protective effects of Ce (III) on photosynthesis in plants were influenced by the intensity of UV-B radiation.

  19. Nanoparticle growth following photochemical α- and β-pinene oxidation at Appledore Island during International Consortium for Research on Transport and Transformation/Chemistry of Halogens at the Isles of Shoals 2004

    NASA Astrophysics Data System (ADS)

    Russell, L. M.; Mensah, A. A.; Fischer, E. V.; Sive, B. C.; Varner, R. K.; Keene, W. C.; Stutz, J.; Pszenny, A. A. P.

    2007-05-01

    Nanoparticle events were observed 48 times in particle size distributions at Appledore Island during the International Consortium for Atmospheric Research on Transport and Transformation/Chemistry of Halogens on the Isles of Shoals (ICARTT/CHAiOS) field campaign from 2 July to 12 August of 2004. Eighteen of the nanoparticle events showed particle growth and occurred during mornings when peaks in mixing ratios of α- and β-pinene and ozone made production of condensable products from photochemical oxidation probable. Many pollutants and other potential precursors for aerosol formation were also at elevated mixing ratios during these events, including NO, HNO3, NH3, HCl, propane, and several other volatile organic carbon compounds. There were no consistent changes in particle composition, although both submicron and supermicron particles included high maximum concentrations of methane sulfonate, sulfate, iodide, nitrate, and ammonium during these events. Nanoparticle growth continued over several hours with a nearly linear rate of increase of diameter with time. The observed nanoparticle growth rates varied from 3 to 13 nm h-1. Apparent nanoparticle aerosol mass fractions (yields) were estimated to range from less than 0.0005 to almost 1 using α- and β-pinene as the presumed particle source. These apparent high aerosol mass fractions (yields) at low changes in aerosol mass are up to two orders of magnitude greater than predictions from extrapolated laboratory parameterizations and may provide a more accurate assessment of secondary organic aerosol formation for estimating the growth of nanoparticles in global models.

  20. Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

    PubMed

    Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

    2016-08-10

    We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics.

  1. Catalysis of Photochemical Reactions.

    ERIC Educational Resources Information Center

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  2. A theoretical approach to the photochemical activation of matrix isolated aluminum atoms and their reaction with methane

    SciTech Connect

    Pacheco-Blas, M. A.; Novaro, O. A.; Pacheco-Sanchez, J. H.

    2010-11-07

    The photochemical activation of Al atoms in cryogenic matrices to induce their reaction with methane has been experimentally studied before. Here, a theoretical study of the nonadiabatic transition probabilities for the ground ({sup 2}P:3s{sup 2}3p{sup 1}) and the lowest excited states ({sup 2}S:3s{sup 2}4s{sup 1} and {sup 2}D:3s{sup 2}3d{sup 1}) of an aluminum atom interacting with a methane molecule (CH{sub 4}) was carried out through ab initio Hartree-Fock self-consistent field calculations. This was followed by a multiconfigurational study of the correlation energy obtained by extensive variational and perturbational configuration interaction analyses using the CIPSI program. The {sup 2}D state is readily inserted into a C-H bond, this being a prelude to a sequence of avoided crossings with the initially repulsive (to CH{sub 4}) lower lying states {sup 2}P and {sup 2}S. We then use a direct extension of the Landau-Zener theory to obtain transition probabilities at each avoided crossing, allowing the formation of an HAlCH{sub 3} intermediate that eventually leads to the final pair of products H+AlCH{sub 3} and HAl+CH{sub 3}.

  3. Remotely activated protein-producing nanoparticles.

    PubMed

    Schroeder, Avi; Goldberg, Michael S; Kastrup, Christian; Wang, Yingxia; Jiang, Shan; Joseph, Brian J; Levins, Christopher G; Kannan, Sneha T; Langer, Robert; Anderson, Daniel G

    2012-06-13

    The development of responsive nanomaterials, nanoscale systems that actively respond to stimuli, is one general goal of nanotechnology. Here we develop nanoparticles that can be controllably triggered to synthesize proteins. The nanoparticles consist of lipid vesicles filled with the cellular machinery responsible for transcription and translation, including amino acids, ribosomes, and DNA caged with a photolabile protecting group. These particles served as nanofactories capable of producing proteins including green fluorescent protein (GFP) and enzymatically active luciferase. In vitro and in vivo, protein synthesis was spatially and temporally controllable, and could be initiated by irradiating micrometer-scale regions on the time scale of milliseconds. The ability to control protein synthesis inside nanomaterials may enable new strategies to facilitate the study of orthogonal proteins in a confined environment and for remotely activated drug delivery.

  4. Streptomycin affects the growth and photochemical activity of the alga Chlorella vulgaris.

    PubMed

    Perales-Vela, Hugo Virgilio; García, Roberto Velasco; Gómez-Juárez, Evelyn Alicia; Salcedo-Álvarez, Martha Ofelia; Cañizares-Villanueva, Rosa Olivia

    2016-10-01

    Antibiotics are increasingly being used in human and veterinary medicine, as well as pest control in agriculture. Recently, their emergence in the aquatic environment has become a global concern. The aim of this study was to evaluate the effect of streptomycin on growth and photosynthetic activity of Chlorella vulgaris after 72h exposure. We found that growth, photosynthetic activity and the content of the D1 protein of photosystem II decreased. Analysis of chlorophyll a fluorescence emission shows a reduction in the energy transfer between the antenna complex and reaction center. Also the activity of the oxygen evolution complex and electron flow between QA and QB were significantly reduced; in contrast, we found an increase in the reduction rate of the acceptor side of photosystem I. The foregoing can be attributed to the inhibition of the synthesis of the D1 protein and perhaps other coded chloroplast proteins that are part of the electron transport chain which are essential for the transformation of solar energy in the photosystems. We conclude that micromolar concentrations of streptomycin can affect growth and photosynthetic activity of Chlorella vulgaris. The accumulation of antibiotics in the environment can become an ecological problem for primary producers in the aquatic environment.

  5. Changes in antibacterial activity of triclosan and sulfa drugs due to photochemical transformations.

    PubMed

    Wammer, Kristine H; Lapara, Timothy M; McNeill, Kristopher; Arnold, William A; Swackhamer, Deborah L

    2006-06-01

    Sulfa drugs and triclosan represent two classes of antibacterials that have been found in natural waters and for which photodegradation is anticipated to be a significant loss process. Parent antibacterial compounds and the products of photolysis reactions were compared for three sulfa drugs and triclosan to determine the extent to which photolysis affects their antibacterial potency on Escherichia coli DH5alpha. Sulfathiazole (median effective concentration [EC50] = 20.0 microM), sulfamethoxazole (EC50 = 12.3 microM), and sulfachloropyridazine (EC50 = 6.9 microM) inhibited bacterial growth but did not affect respiratory activity. Photolysis products of these sulfa drugs did not retain any measurable ability to inhibit growth. Triclosan inhibited both the growth (EC50 = 0.24 microM) and respiratory activity of E. coli DH5alpha. Triclosan photolysis products also exhibited no measurable effect on growth or respiratory activity. These experiments indicate that the products of triclosan and sulfa drug photolysis are unlikely to possess antibacterial activity in natural waters. The rapid screening method used for these two classes of compounds will be useful for helping to identify photolabile antibacterial compounds, for which photoproducts could require further investigation.

  6. Chlorophyll composition and photochemical activity of photosystems detached from chloroplast grana and stroma lamellae.

    PubMed

    Gasanov, R A; French, C S

    1973-07-01

    A stroma fraction that has photosystem 1 activity and grana lamellae fractions that have activities for both photosystems were isolated by differential centrifugation of a needle valve homogenate. Subsequent fractions, corresponding to photosystems 1 (F-1D) and 2 (F-2D) were isolated by digitonin treatment of the grana lamellae (P-10K) and compared with respect to their chlorophyll composition and electron transport activities.Fraction F-2D from grana lamellae having photosystem 2 activity is primarily active in photosystem 2 and contains only the four major forms of chlorophyll a with a predominance of chlorophyll a 677 nm. This fraction differs from the original grana membranes in the absence of the longwavelength form of chlorophyll a and in the widening of the absorption band of chlorophyll a 682 nm from 10.9 to 15.6 nm.Photosystem 1 particles from grana and stroma both have high photosystem 1 activity but differ from each other in the proportions of the four major forms of chlorophyll a. The short-wavelength forms of chlorophyll a and also chlorophyll b 650 nm in particles from grana lamellae comprise relatively more total area than these same forms in the particles from stroma. In addition, the fraction corresponding to photosystem 1 from grana lamellae is not shifted to the long-wavelength side of the main absorption maximum, as compared to the photosystem 2 particles from grana and the original grana membrane fraction; this is usually observed in fractions that have photosystem 1 activity. Furthermore, the longest wavelength form of chlorophyll a in the photosystem 1 particles from grana is at 700 nm, while in the same fraction from stroma, it is at 706 nm.The half-width of the four main forms of chlorophyll a and both forms of chlorophyll b in the photosystem 1 fraction from grana is narrower than that of the corresponding forms in the same fraction from stroma. This may indicate a different packing of pigment molecules that are aggregated on the surface

  7. Photochemical Decoration of Silver Nanocrystals on Magnetic MnFe2O4 Nanoparticles and Their Applications in Antibacterial Agents and SERS-Based Detection

    NASA Astrophysics Data System (ADS)

    Huy, Le Thanh; Tam, Le Thi; Van Son, Tran; Cuong, Nguyen Duy; Nam, Man Hoai; Vinh, Le Khanh; Huy, Tran Quang; Ngo, Duc-The; Phan, Vu Ngoc; Le, Anh-Tuan

    2017-01-01

    In this study, multifunctional nanocomposites consisting of silver nanoparticles and manganese ferrite nanoparticles (Ag-MnFe2O4) were successfully synthesized using a two-step chemical process. The formation of Ag-MnFe2O4 nanocomposites were analyzed by transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy measurements. Noticeable antibacterial activity of the Ag-MnFe2O4 nanocomposites was demonstrated against two Gram-negative bacteria, Salmonella enteritidis and Klebsiella pneumoniae. A direct-drop diffusion method can be an effective way to investigate the antibacterial effects of nanocomposite samples. Interestingly, we also demonstrated the use of Ag-MnFe2O4 nanocomposites as a surface-enhanced Raman scattering (SERS) platform to detect and quantify trace amounts of organic dye in water solutions. The combination of Ag and MnFe2O4 nanoparticles opens opportunities for creating advantages such as targeted bactericidal delivery, recyclable capability, and sensitive SERS-based detection for advanced biomedicine and environmental monitoring applications.

  8. [Effect of metalloproteins on the photochemical activity of chloroplasts treated with polyene antibiotics].

    PubMed

    Mutuskin, A A; Makovkina, L E; Pshenova, K V; Vostroknutova, G N

    1977-04-01

    The effects of various metall-containing proteins (plastocyanin, plantacyanin, azurine and cytochromes of the f type) on the activity of photosystem I of chloroplasts, treated with polyene antibiotics, were studied. The inhibiting effect of the polyenes, surgumycin and philipin, was completely removed by an addition of copper-containing protein plastocyanin. No similar effect was exerted by other Cu-containing proteins--azurine and plantacyanin. The cytochromes of the f type isolated from the green algae chlorella, blue-green algae spiruline and aphanezomenone, having different electrophoretic properties, restored the activity of photosystem I of chloroplasts incubated with antibiotics in a different degree. Acid cytochrome f of chlorella restored the activity by 80--100%; less acid cytochrome f from spiruline-only by 50%. The least restoring effect was exerted by aphanezomenone cytochrome, which possesses some basic properties. The chloroplasts treatment with surgumycin did not affect the isolation of the terminal enzyme of the chloroplast electron-transporting chain of ferredoxin--NADP--reductase. Possible environment of plastocyanin in the chloroplast membrane and the mechanism of photosystem I restoration are discussed.

  9. Identification of Volatile Organic Compounds (VOCs) From Photochemical Activity in Snow Samples

    NASA Astrophysics Data System (ADS)

    Kos, G.; Ariya, P. A.

    2004-05-01

    The occurrence of VOCs in snow has been observed and can be related to anthropogenic emissions and biological activity. Photochemistry and microorganisms play a major role in the transformation of compounds in different compartments of the global ecosystem. Studies so far focused on the determination of single analytes or a class of compounds - mainly of anthropogenic origin (e.g. halogenated aromatic hydrocarbons) - that were considered important with regard to health and environmental concerns. Broader studies that describe a range of different compounds with different functionalities are relatively rare, especially for those of biological origin. The presented study investigated the formation of VOCs in snow samples and their connection with microbiological activity. The main aim was to pre-concentrate, identify and quantify volatile organic compounds. Snow samples were collected in an urban environment (Montreal, Canada) with sterilized containers. Samples were transferred into a heated reaction flask, where the sample was melted. A two-trap system was employed for pre-concentration: The first trap was used for water removal. The second trap was used for the collection of expected analytes by removing volatiles from the circulating air. Circulation was maintained with a pump at atmospheric pressure. Adsorption to glass walls of the reaction flask was prevented with halocarbon wax coating. Different sterilization methods were employed to suppress microbiological activity in order to collect background data and identify compounds of biological origin. VOC concentration and compound identification was performed with gas chromatography and mass spectrometric detection (GC-MS) by taking a sample with a gas-tight syringe through a septum-port. The sample was directly injected into the GC system. Compounds were identified by their respective mass spectra and included aldehydes and alcohols.

  10. Computational Studies of CO2 Activation via Photochemical Reactions with Reduced Sulfur Compounds

    PubMed Central

    Baltrusaitis, Jonas; Patterson, Eric; Hatch, Courtney

    2012-01-01

    Reactions between CO2 and reduced sulfur compounds (RSC) - H2S and CH3SH - were investigated using ground and excited state density functional theory (DFT) and coupled cluster (CC) methods to explore possible RSC oxidation mechanisms and CO2 activation mechanisms in the atmospheric environment. Ground electronic state calculations at the CR-CC(2,3)/6-311+G(2df,2p)//CAM-B3LYP/6-311+G(2df,2p) level show proton transfer as a limiting step in the reduction of CO2 with activation energies of 49.64 and 47.70 kcal/mol, respectively, for H2S and CH3SH. On the first excited state surface, CR-EOMCC(2,3)/6-311+G(2df,2p)//CAM-B3LYP/6-311+G(2df,2p) calculations reveal that energies of <250 nm are needed to form H2S-CO2 and CH3SH-CO2 complexes allowing facile hydrogen atom transfer. Once excited, all reaction intermediates and transition states are downhill energetically showing either C-H or C-S bond formation in the excited state whereas only C-S bond formation was found in the ground state. Environmental implications of these data are discussed with a focus on tropospheric reactions between CO2 and RSC, as well as potential for carbon sequestration using photocatalysis. PMID:22920727

  11. The effect of charged lipids on bacteriorhodopsin membrane reconstitution and its photochemical activities

    SciTech Connect

    Wang Zhen; Bai Jing; Xu Yuhong

    2008-07-11

    Bacteriorhodopsin (BR) was reconstituted into artificial lipid membrane containing various charged lipid compositions. The proton pumping activity of BR under flash and continuous illumination, proton permeability across membrane, as well as the decay kinetics of the photocycle intermediate M{sub 412} were studied. The results showed that lipid charges would significantly affect the orientation of BR inserted into lipid membranes. In liposomes containing anionic lipids, BRs were more likely to take natural orientation as in living cells. In neutral or positively charged liposomes, most BRs were reversely assembled, assuming an inside out orientation. Moreover, the lipids charges also affect BR's M intermediate kinetics, especially the slow component in M intermediate decay. The half-life M{sub 412s} increased significantly in BRs in liposomes containing cationic lipids, while decreased in those in anionic liposomes.

  12. Effect of leaf dehydration duration and dehydration degree on PSII photochemical activity of papaya leaves.

    PubMed

    Liu, Meijun; Zhang, Zishan; Gao, Huiyuan; Yang, Cheng; Fan, Xingli; Cheng, Dandan

    2014-09-01

    Although the effect of dehydration on photosynthetic apparatus has been widely studied, the respective effect of dehydration duration and dehydration degree was neglected. This study showed that, when leaves dehydrated in air, the PSII activities of leaves decreased with the decline of leaf relative water content (RWC). Unexpectedly, when leaves dehydrated to same RWC, the decreases in Fv/Fm, Ψo and RC/CSm were lower in leaves dehydrating at 43 °C than those at 25 °C. However, to reach the same RWC, leaves dehydrating at 43 °C experienced 1/6 of the dehydration duration for leaves dehydrating at 25 °C. To distinguish the respective effect of dehydration degree and dehydration duration on photosynthetic apparatus, we studied the PSII activities of leaves treated with different concentration of PEG solutions. Increasing dehydration degree aggravated the decline of Fv/Fm, Ψo and RC/CSm in leaves with the same dehydration duration, while prolonging the dehydration duration also exacerbated the decline of Fv/Fm, Ψo and RC/CSm in leaves with identical dehydration degree. With the same dehydration degree and duration, high temperature enhanced the decrease of Fv/Fm, Ψo and RC/CSm in the leaves. When leaves dehydrated in air, the effect of high temperature was underestimated due to reduction of dehydration duration. The results demonstrated that, dehydration degree and duration both play important roles in damage to photosynthetic apparatus. We suggest that, under combined stresses, the effects of dehydration degree and duration on plants should be considered comprehensively, otherwise, partial or incorrect results may be obtained.

  13. Photochemical aging of secondary organic aerosols: effects on hygroscopic growth and CCN activation

    NASA Astrophysics Data System (ADS)

    Buchholz, A.; Mentel, Th. F.; Tillmann, R.; Schlosser, E.; Mildenberger, K.; Clauss, T.; Henning, S.; Kiselev, A.; Stratmann, F.

    2009-04-01

    Plant emitted volatile organic carbons (VOCs) are a major precursor of secondary organic aerosols (SOA), an important constituent of atmospheric aerosols. The precursors are oxidized via ozonolysis, photooxidation, or by NO3 and form aerosol particles. Due to further oxidation of the organic matter the composition of the SOA may age with time. This will also change the hygroscopic growth (HG) and cloud condensation nuclei (CCN) activation of the particles. In this study we generated and aged SOA in the SAPHIR chamber at the Research Centre Juelich under near atmospheric conditions: natural sunlight, low precursor and O3 concentrations, and long reaction times. As precursor we used a mixture of 5 monoterpenes (MT) or 5 MT with 2 sesquiterpenes which had been identified as major constituents of plant emissions in previous experiments. Concentrations ranged between 4 and 100 ppb MT and the total reaction time was 36h. HG was measured at RH=10-97% by a Hygroscopic Tandem Differential Analyser (HTDMA, FZ Juelich) and at RH=97-99% by the Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile, IfT Leipzig). The agreement between HTDMA and LACIS-mobile data was generally good. CCN properties were measured with a continuous flow CCN Counter from DMT. SOA particles generated on a sunny day were more hygroscopic and had a lower activation diameter (Dcrit) than SOA formed under cloudy conditions. With aging it became more hygroscopic and Dcrit decreased. Sunlight enhanced this effect. But the change in HG and Dcrit due to aging was less than the difference between SOA generated under different conditions (i.e. sunny or cloudy). We did not observe a dependence of the HG on the precursor concentration.

  14. Non-photochemical production of singlet oxygen via activation of persulfate by carbon nanotubes.

    PubMed

    Cheng, Xin; Guo, Hongguang; Zhang, Yongli; Wu, Xiao; Liu, Yang

    2017-02-08

    The reaction between persulfate (PS) and carbon nanotubes (CNTs) for the degradation of 2,4-dichlorophenol (2,4-DCP) was investigated. It was demonstrated that CNTs could efficiently activate PS for the degradation of 2,4-DCP. Results suggested that the neither hydroxyl radical (OH) nor sulfate radical (SO4(-)) was produced therein. For the first time, the generation of singlet oxygen ((1)O2) was proved by several methods including electron paramagnetic resonance spectrometry (EPR) and liquid chromatography mass spectrometry measurements. Moreover, the generation of the superoxide radical as a precursor of the singlet oxygen was also confirmed by using certain scavengers and EPR measurement, in which the presence of molecular oxygen was not required as a precursor of (1)O2. The efficient generation of (1)O2 using the PS/CNTs system without any light irradiation can be employed for the selective oxidation of aqueous organic compounds under neutral conditions with the mineralization and toxicity evaluated. A kinetic model was developed to theoretically evaluate the adsorption and oxidation of 2,4-DCP on the CNTs. Accordingly, a catalytic mechanism was proposed involving the formation of a dioxirane intermediate between PS and CNTs, and the subsequent decomposition of this intermediate into (1)O2.

  15. An influence of solar activity on latitudinal distribution of atmospheric ozone and temperature in 2-D radiative-photochemical model

    NASA Technical Reports Server (NTRS)

    Dyominov, I. G.

    1989-01-01

    On the basis of the 2-D radiative-photochemical model of the ozone layer at heights 0 to 60 km in the Northern Hemisphere there are revealed and analyzed in detail the characteristic features of the season-altitude-latitude variations of ozone and temperature due to changes of the solar flux during the 11 year cycle, electron and proton precipitations.

  16. Antimicrobial Activity of Carbon-Based Nanoparticles

    PubMed Central

    Maleki Dizaj, Solmaz; Mennati, Afsaneh; Jafari, Samira; Khezri, Khadejeh; Adibkia, Khosro

    2015-01-01

    Due to the vast and inappropriate use of the antibiotics, microorganisms have begun to develop resistance to the commonly used antimicrobial agents. So therefore, development of the new and effective antimicrobial agents seems to be necessary. According to some recent reports, carbon-based nanomaterials such as fullerenes, carbon nanotubes (CNTs) (especially single-walled carbon nanotubes (SWCNTs)) and graphene oxide (GO) nanoparticles show potent antimicrobial properties. In present review, we have briefly summarized the antimicrobial activity of carbon-based nanoparticles together with their mechanism of action. Reviewed literature show that the size of carbon nanoparticles plays an important role in the inactivation of the microorganisms. As major mechanism, direct contact of microorganisms with carbon nanostructures seriously affects their cellular membrane integrity, metabolic processes and morphology. The antimicrobial activity of carbon-based nanostructures may interestingly be investigated in the near future owing to their high surface/volume ratio, large inner volume and other unique chemical and physical properties. In addition, application of functionalized carbon nanomaterials as carriers for the ordinary antibiotics possibly will decrease the associated resistance, enhance their bioavailability and provide their targeted delivery. PMID:25789215

  17. The response of Hordeum spontaneum desert ecotype to drought and excessive light intensity is characterized by induction of O2 dependent photochemical activity and anthocyanin accumulation.

    PubMed

    Eppel, Amir; Keren, Nir; Salomon, Eitan; Volis, Sergei; Rachmilevitch, Shimon

    2013-03-01

    The goal of the current research was to study the role of anthocyanin accumulation, O(2)-related photochemical processes and non-photochemical quenching (NPQ) in the response of desert and Mediterranean plants to drought and excessive light. Plants of Hordeum spontaneum were collected from Mediterranean and desert environments and were subjected to terminal drought for 25 days and then measured for PSII yield at 2 and 21% O(2), NPQ, net carbon assimilation, stomatal conductance, leaf relative water content (LRWC), anthocyanin concentration and leaf absorbance. Under terminal drought, LRWC, carbon assimilation and stomatal conductance decreased similarly and significantly in both the Mediterranean and the desert ecotypes. Anthocyanin accumulated more in the desert ecotype than in the Mediterranean ecotype. NPQ increased more in the Mediterranean ecotype as compared with the desert ecotype. PSII yield decreased significantly in the Mediterranean ecotype under drought and was much lower than in the desert ecotype under drought. The relatively high PSII yield under drought in the desert ecotype was O(2) dependent. The response of the H. spontaneum ecotype from a desert environment to drought stress was characterized by anthocyanin accumulation and induction of O(2) dependent photochemical activity, while the response of the Mediterranean ecotype was based on a higher induction of NPQ.

  18. Enhanced antiviral activity of acyclovir loaded into nanoparticles.

    PubMed

    Cavalli, Roberta; Donalisio, Manuela; Bisazza, Agnese; Civra, Andrea; Ranucci, Elisabetta; Ferruti, Paolo; Lembo, David

    2012-01-01

    The activity of antivirals can be enhanced by their incorporation in nanoparticulate delivery systems. Peculiar polymeric nanoparticles, based on a β-cyclodextrin-poly(4-acryloylmorpholine) monoconjugate (β-CD-PACM), are proposed as acyclovir carriers. The experimental procedure necessary to obtain the acyclovir-loaded nanoparticles using the solvent displacement preparation method will be described in this chapter. Fluorescent labeled nanoparticles are prepared using the same method for cellular trafficking studies. The biocompatibility assays necessary to obtain safe nanoparticles are reported. Section 4 of this chapter describes the assessment of the antiviral activity of the acyclovir-loaded nanoparticles.

  19. Antimicrobial activity of biogenic silver nanoparticles, and silver chloride nanoparticles: an overview and comments.

    PubMed

    Durán, Nelson; Nakazato, Gerson; Seabra, Amedea B

    2016-08-01

    The antimicrobial impact of biogenic-synthesized silver-based nanoparticles has been the focus of increasing interest. As the antimicrobial activity of nanoparticles is highly dependent on their size and surface, the complete and adequate characterization of the nanoparticle is important. This review discusses the characterization and antimicrobial activity of biogenic synthesized silver nanoparticles and silver chloride nanoparticles. By revising the literature, there is confusion in the characterization of these two silver-based nanoparticles, which consequently affects the conclusion regarding to their antimicrobial activities. This review critically analyzes recent publications on the synthesis of biogenic silver nanoparticles and silver chloride nanoparticles by attempting to correlate the characterization of the nanoparticles with their antimicrobial activity. It was difficult to correlate the size of biogenic nanoparticles with their antimicrobial activity, since different techniques are employed for the characterization. Biogenic synthesized silver-based nanoparticles are not completely characterized, particularly the nature of capped proteins covering the nanomaterials. Moreover, the antimicrobial activity of theses nanoparticles is assayed by using different protocols and strains, which difficult the comparison among the published papers. It is important to select some bacteria as standards, by following international foundations (Pharmaceutical Microbiology Manual) and use the minimal inhibitory concentration by broth microdilution assays from Clinical and Laboratory Standards Institute, which is the most common assay used in antibiotic ones. Therefore, we conclude that to have relevant results on antimicrobial effects of biogenic silver-based nanoparticles, it is necessary to have a complete and adequate characterization of these nanostructures, followed by standard methodology in microbiology protocols.

  20. Physicochemical signatures of nanoparticle-dependent complement activation

    SciTech Connect

    Thomas, Dennis G.; Chikkagoudar, Satish; Heredia-Langner, Alejandro; Tardiff, Mark F.; Xu, Zhixiang; Hourcade, Dennis; Pham, Christine; Lanza, Gregory M.; Weinberger, Kilian Q.; Baker, Nathan A.

    2014-03-21

    Nanoparticles are potentially powerful therapeutic tools that have the capacity to target drug payloads and imaging agents. However, some nanoparticles can activate complement, a branch of the innate immune system, and cause adverse side-effects. Recently, we developed an in vitro hemolytic assay protocol for measuring the nanoparticle-dependent complement activity of serum samples and applied this protocol to several nanoparticle formulations that differed in size, surface charge, and surface chemistry; quantifying the nanoparticle-dependent complement activity using a metric called Residual Hemolytic Activity (RHA). In the present work, we have used a decision tree learning algorithm to derive the rules for estimating nanoparticle-dependent complement response based on the data generated from the hemolytic assay studies. Our results indicate that physicochemical properties of nanoparticles, namely, size, polydispersity index, zeta potential, and mole percentage of the active surface ligand of a nanoparticle, can serve as good descriptors for prediction of nanoparticle-dependent complement activation in the decision tree modeling framework. The robustness and predictability of the model can be improved by training the model with additional data points that are uniformly distributed in the RHA/physicochemical descriptor space and by incorporating instability effects on nanoparticle physicochemical properties into the model.

  1. Synthesis of cobalt ferrite nanoparticles from thermolysis of prospective metal-nitrosonaphthol complexes and their photochemical application in removing methylene blue

    NASA Astrophysics Data System (ADS)

    Tavana, Jalal; Edrisi, Mohammad

    2016-03-01

    In this study, cobalt ferrite (CoFe2O4) nanoparticles were synthesized by two novel methods. The first method is based on the thermolysis of metal-NN complexes. In the second method, a template free sonochemical treatment of mixed cobalt and iron chelates of α-nitroso-β-naphthol (NN) was applied. Products prepared through method 1 were spherical, with high specific surface area (54.39 m2 g-1) and small average crystalline size of 13 nm. However, CoFe2O4 nanoparticles prepared by method 2 were in random shapes, a broad range of crystalline sizes and a low specific surface area of 25.46 m2 g-1 though highly pure. A Taguchi experimental design was implemented in method 1 to determine and obtain the optimum catalyst. The structural and morphological properties of products were investigated by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, Brunauer-Emmett-Teller and dynamic laser light scattering. The crystalline size calculations were performed using Williamson-Hall method on XRD spectrum. The photocatalytic activity of the optimum nanocrystalline cobalt ferrite was investigated for degradation of a representative pollutant, methylene blue (MB), and visible light as energy source. The results showed that some 92% degradation of MB could be achieved for 7 h of visible light irradiation.

  2. Water-dispersible silver nanoparticles-decorated carbon nanomaterials: synthesis and enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Dinh, Ngo Xuan; Chi, Do Thi; Lan, Nguyen Thi; Lan, Hoang; Van Tuan, Hoang; Van Quy, Nguyen; Phan, Vu Ngoc; Huy, Tran Quang; Le, Anh-Tuan

    2015-04-01

    In recent years, a growing number of outbreak of infectious diseases have emerged all over the world. The outbreak of re-emerging and emerging infectious diseases is a considerable burden on global economies and public health. Nano-antimicrobials have been studied as an effective solution for the prevention of infectious diseases. In this work, we demonstrated a modified photochemical approach for the preparation of carbon nanotubes-silver nanoparticles (CNTs-Ag) and graphene oxide-silver nanoparticles (GO-Ag) nanocomposites, which can be stably dispersible in aqueous solution. The formation of silver nanoparticles (Ag-NPs) on the functionalized CNTs and GO nanosheets was analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and UV-Vis measurements. These analyses indicated that the average particle sizes of Ag-NPs deposited on GO/CNTs nanostructures were ~6-7 nm with nearly uniform size distribution. Moreover, these nanocomposites were found to exhibit enhanced antibacterial activity against two strains of infectious bacteria including Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria as compared to bare Ag-NPs. Our obtained studies showed a high potential of GO-Ag and CNTs-Ag nanocomposites as effective and long-term disinfection solution to eliminate infectious bacterial pathogens.

  3. Identification of the Active Species in Photochemical Hole Scavenging Reactions of Methanol on TiO2

    SciTech Connect

    Shen, Mingmin; Henderson, Michael A.

    2011-11-03

    Molecular and dissociative methanol adsorption species were prepared on rutile TiO2(110) surfaces to study photocatalytic oxidation of methanol in ultrahigh vacuum (UHV) using temperature-programmed desorption (TPD). Adsorbed methoxy groups (CH3O-) were found to be the photoactive form of adsorbed methanol converted to adsorbed formaldehyde and a surface OH group by hole-mediated C-H bond cleavage. These results suggest that adsorbed methoxy is the effective hole scavenger in photochemical reactions involving methanol.

  4. Antifungal activity of gold nanoparticles prepared by solvothermal method

    SciTech Connect

    Ahmad, Tokeer; Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna; Manzoor, Nikhat; Ahmad, Aijaz; Ahmed, Jahangeer; Al-Shihri, Ayed S.

    2013-01-15

    Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m{sup 2/}g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.

  5. Cu/Zn superoxide dismutase and catalase activities in Pinus mugo needles growing at elevated stands in the mountains, and their photochemical efficiency of PSII.

    PubMed

    Miszalski, Zbigniew; Libik, Marta; Surówka, Ewa; Niewiadomska, Ewa

    2005-08-01

    Pinus mugo needles were sampled at different altitudes (1420, 1590 and 1920 m a.s.l.) to analyse levels of oxidative stress and changes in maximum photochemical efficiency of PSII. Polyacrylamide gel electrophoresis demonstrated that almost all superoxide dismutase activity represented Cu/Zn superoxide dismutase, and only 4-6% represents Mn superoxide dismutase. In extracts from plants sampled at 1590 and 1920 m a.s.l., lower activity of Cu/Zn superoxide dismutase was found. Comparing these data with immunoblots, it can be concluded that the differences in superoxide dismutase activity was related to protein amount. In needles from higher altitudes, a decrease in catalase activity was detected, as opposed to the protein amount, which was higher in needles from the higher stands. Considering the decrease in catalase and Cu/Zn superoxide dismutase activities in needles collected at 1590 and 1920 m a.s.l., we suggest that higher levels of oxidative stress may induce changes in photochemical efficiency of PSII.

  6. Antibacterial and catalytic activities of green synthesized silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Bindhu, M. R.; Umadevi, M.

    2015-01-01

    The aqueous beetroot extract was used as reducing agent for silver nanoparticles synthesis. The synthesized nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface plasmon resonance peak of synthesized nanoparticles was observed at 438 nm. As the concentration of beetroot extract increases, absorption spectra shows blue shift with decreasing particle size. The prepared silver nanoparticles were well dispersed, spherical in shape with the average particle size of 15 nm. The prepared silver nanoparticles are effective in inhibiting the growth of both gram positive and gram negative bacteria. The prepared silver nanoparticles reveal faster catalytic activity. This natural method for synthesis of silver nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology avoiding the presence of hazardous and toxic solvents and waste.

  7. Antibacterial and catalytic activities of green synthesized silver nanoparticles.

    PubMed

    Bindhu, M R; Umadevi, M

    2015-01-25

    The aqueous beetroot extract was used as reducing agent for silver nanoparticles synthesis. The synthesized nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface plasmon resonance peak of synthesized nanoparticles was observed at 438 nm. As the concentration of beetroot extract increases, absorption spectra shows blue shift with decreasing particle size. The prepared silver nanoparticles were well dispersed, spherical in shape with the average particle size of 15 nm. The prepared silver nanoparticles are effective in inhibiting the growth of both gram positive and gram negative bacteria. The prepared silver nanoparticles reveal faster catalytic activity. This natural method for synthesis of silver nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology avoiding the presence of hazardous and toxic solvents and waste.

  8. Anti-proliferative activity of silver nanoparticles

    PubMed Central

    AshaRani, PV; Hande, M Prakash; Valiyaveettil, Suresh

    2009-01-01

    Background Nanoparticles possess exceptional physical and chemical properties which led to rapid commercialisation. Silver nanoparticles (Ag-np) are among the most commercialised nanoparticles due to their antimicrobial potential. Ag-np based cosmetics, therapeutic agents and household products are in wide use, which raised a public concern regarding their safety associated with human and environmental use. No safety regulations are in practice for the use of these nanomaterials. The interactions of nanomaterials with cells, uptake mechanisms, distribution, excretion, toxicological endpoints and mechanism of action remain unanswered. Results Normal human lung fibroblasts (IMR-90) and human glioblastoma cells (U251) were exposed to different doses of Ag-nps in vitro. Uptake of Ag-nps occurred mainly through endocytosis (clathrin mediated process and macropinocytosis), accompanied by a time dependent increase in exocytosis rate. The electron micrographs revealed a uniform intracellular distribution of Ag-np both in cytoplasm and nucleus. Ag-np treated cells exhibited chromosome instability and mitotic arrest in human cells. There was efficient recovery from arrest in normal human fibroblasts whereas the cancer cells ceased to proliferate. Toxicity of Ag-np is mediated through intracellular calcium (Ca2+) transients along with significant alterations in cell morphology and spreading and surface ruffling. Down regulation of major actin binding protein, filamin was observed after Ag-np exposure. Ag-np induced stress resulted in the up regulation of metallothionein and heme oxygenase -1 genes. Conclusion Here, we demonstrate that uptake of Ag-np occurs mainly through clathrin mediated endocytosis and macropinocytosis. Our results suggest that cancer cells are susceptible to damage with lack of recovery from Ag-np-induced stress. Ag-np is found to be acting through intracellular calcium transients and chromosomal aberrations, either directly or through activation of

  9. Sunlight-driven photo-transformation of bisphenol A by Fe(III) in aqueous solution: Photochemical activity and mechanistic aspects.

    PubMed

    Pan, Meilan; Ding, Jie; Duan, Lin; Gao, Guandao

    2017-01-01

    Iron is one of the most abundant elements in aquatic environments, and plays important roles in the fate and transport of environmental contaminants. Previous studies on the photochemical properties of Fe(III) species have largely focused on complexes formed between Fe(III) and environmental ligands such as natural organic matter (NOM) under UV irradiation, whereas the potentially important roles of hydrolysis species of Fe(III) in Fe(III)-mediated photo-transformation of environmental contaminants under solar light are not fully understood. In this study, the solar light-driven photochemical activities of hydrolysis species of Fe(III) were further explored, using a system containing only 0.5 mM Fe2(SO4)3 and bisphenol A. The important role of colloidal [Fe(OH)3]m, formed from the hydrolysis of Fe(3+), as a core photochemical species of Fe(III) was proposed and verified. Interestingly, O2(-), rather than OH, was identified (via electron spin resonance) as the key active radical responsible for the degradation of bisphenol A. We propose that unlike Fe(OH)(2+), which under UV irradiation can yield OH (Fe(OH)(2+) + hv → Fe(2+) + OH), colloidal [Fe(OH)3]m produces O2(-) even in sunlight ([Fe(OH)3]m + 2O2 + hv → Fe(II) + 2O2(-) + H2O). The fact that Fe(III) can produce strong radicals in sunlight may have important environmental implications.

  10. The effects of bacteria-nanoparticles interface on the antibacterial activity of green synthesized silver nanoparticles.

    PubMed

    Ahmad, Aftab; Wei, Yun; Syed, Fatima; Tahir, Kamran; Rehman, Aziz Ur; Khan, Arifullah; Ullah, Sadeeq; Yuan, Qipeng

    2017-01-01

    Neutralization of bacterial cell surface potential using nanoscale materials is an effective strategy to alter membrane permeability, cytoplasmic leakage, and ultimate cell death. In the present study, an attempt was made to prepare biogenic silver nanoparticles using biomolecules from the aqueous rhizome extract of Coptis Chinensis. The biosynthesized silver nanoparticles were surface modified with chitosan biopolymer. The prepared silver nanoparticles and chitosan modified silver nanoparticles were cubic crystalline structures (XRD) with an average particle size of 15 and 20 nm respectively (TEM, DLS). The biosynthesized silver nanoparticles were surface stabilized by polyphenolic compounds (FTIR). Coptis Chinensis mediated silver nanoparticles displayed significant activity against E. coli and Bacillus subtilus with a zone of inhibition 12 ± 1.2 (MIC = 25 μg/mL) and 18 ± 1.6 mm (MIC = 12.50 μg/mL) respectively. The bactericidal efficacy of these nanoparticles was considerably increased upon surface modification with chitosan biopolymer. The chitosan modified biogenic silver nanoparticles exhibited promising activity against E. coli (MIC = 6.25 μg/mL) and Bacillus subtilus (MIC = 12.50 μg/mL). Our results indicated that the chitosan modified silver nanoparticles were promising agents in damaging bacterial membrane potential and induction of high level of intracellular reactive oxygen species (ROS). In addition, these nanoparticles were observed to induce the release of the high level of cytoplasmic materials especially protein and nucleic acids into the media. All these findings suggest that the chitosan functionalized silver nanoparticles are efficient agents in disrupting bacterial membrane and induction of ROS leading to cytoplasmic leakage and cell death. These findings further conclude that the bacterial-nanoparticles surface potential modulation is an effective strategy in enhancing the antibacterial potency of silver nanoparticles.

  11. Active Silver Nanoparticles for Wound Healing

    PubMed Central

    Rigo, Chiara; Ferroni, Letizia; Tocco, Ilaria; Roman, Marco; Munivrana, Ivan; Gardin, Chiara; Cairns, Warren R. L.; Vindigni, Vincenzo; Azzena, Bruno; Barbante, Carlo; Zavan, Barbara

    2013-01-01

    In this preliminary study, the silver nanoparticle (Ag NP)-based dressing, Acticoat™ Flex 3, has been applied to a 3D fibroblast cell culture in vitro and to a real partial thickness burn patient. The in vitro results show that Ag NPs greatly reduce mitochondrial activity, while cellular staining techniques show that nuclear integrity is maintained, with no signs of cell death. For the first time, transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS) analyses were carried out on skin biopsies taken from a single patient during treatment. The results show that Ag NPs are released as aggregates and are localized in the cytoplasm of fibroblasts. No signs of cell death were observed, and the nanoparticles had different distributions within the cells of the upper and lower dermis. Depth profiles of the Ag concentrations were determined along the skin biopsies. In the healed sample, most of the silver remained in the surface layers, whereas in the unhealed sample, the silver penetrated more deeply. The Ag concentrations in the cell cultures were also determined. Clinical observations and experimental data collected here are consistent with previously published articles and support the safety of Ag NP-based dressing in wound treatment. PMID:23455461

  12. ACTIVE MEDIA: Photoprocesses in laser-active media operating in the 400 nm range. II. Photochemical processes

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Rimma T.; Kopylova, T. N.; Degtyarenko, K. M.; Sergeev, A. K.; Nesterenko, S. N.; Mayer, G. V.; Afanas'ev, N. B.; Vereskun, V. N.

    1996-09-01

    The quantum yield of phototransformations, the relative yields of photoproducts, and the half-life of active media based on 2-4(pyridyl)-5-(4-methophenyl) oxazole (4PyPO) and of the substituted derivatives of dipyrazolinylbenzene (PDPDP) were investigated as a function of the concentration of the solution, the length of the active medium, and the parameters of the pump pulses generated by an XeCl laser. The results obtained are interpreted with the help of the data on the lasing efficiency and on the induced-absorption spectra.

  13. Multiple active site residues are important for photochemical efficiency in the light-activated enzyme protochlorophyllide oxidoreductase (POR).

    PubMed

    Menon, Binuraj R K; Hardman, Samantha J O; Scrutton, Nigel S; Heyes, Derren J

    2016-08-01

    Protochlorophyllide oxidoreductase (POR) catalyzes the light-driven reduction of protochlorophyllide (Pchlide), an essential, regulatory step in chlorophyll biosynthesis. The unique requirement of the enzyme for light has provided the opportunity to investigate how light energy can be harnessed to power biological catalysis and enzyme dynamics. Excited state interactions between the Pchlide molecule and the protein are known to drive the subsequent reaction chemistry. However, the structural features of POR and active site residues that are important for photochemistry and catalysis are currently unknown, because there is no crystal structure for POR. Here, we have used static and time-resolved spectroscopic measurements of a number of active site variants to study the role of a number of residues, which are located in the proposed NADPH/Pchlide binding site based on previous homology models, in the reaction mechanism of POR. Our findings, which are interpreted in the context of a new improved structural model, have identified several residues that are predicted to interact with the coenzyme or substrate. Several of the POR variants have a profound effect on the photochemistry, suggesting that multiple residues are important in stabilizing the excited state required for catalysis. Our work offers insight into how the POR active site geometry is finely tuned by multiple active site residues to support enzyme-mediated photochemistry and reduction of Pchlide, both of which are crucial to the existence of life on Earth.

  14. Photochemical Modeling Applications

    EPA Pesticide Factsheets

    Provides access to modeling applications involving photochemical models, including modeling of ozone, particulate matter (PM), and mercury for national and regional EPA regulations such as the Clean Air Interstate Rule (CAIR) and the Clean Air Mercury Rule

  15. Antimicrobial activity of silver nanoparticles impregnated wound dressing

    NASA Astrophysics Data System (ADS)

    Shinde, V. V.; Jadhav, P. R.; Patil, P. S.

    2013-06-01

    In this work, silver nanoparticles were synthesized by simple wet chemical reduction method. The silver nitrate was reduced by Sodium borohydride used as reducing agent and Poly (vinyl pyrrolidone) (PVP) as stabilizing agent. The formation of silver nanoparticles was evaluated by UV-visible spectroscope and transmission electron microscope (TEM). Absorption spectrum consist two plasmon peaks at 410 and 668 nm revels the formation of anisotropic nanoparticles confirmed by TEM. The formation of silver nanoparticles was also evidenced by dynamic light scattering (DLS) study. DLS showed polydisperse silver nanoparticles with hydrodynamic size 32 nm. Protecting mechanism of PVP was manifested by FT-Raman study. Silver nanoparticles were impregnated into wound dressing by sonochemical method. The Kirby-Bauer disc diffusion methods were used for antimicrobial susceptibility testing. The antimicrobial activity of the samples has been tested against gram-negative bacterium Escherichia coli and gram-positive bacterium Staphylococcus aureus.

  16. Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Bindhu, M. R.; Sathe, V.; Umadevi, M.

    2013-11-01

    Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439 nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14 nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons.

  17. Porous Collagen Scaffold Reinforced with Surfaced Activated PLLA Nanoparticles

    PubMed Central

    Xu, Cancan; Lu, Wei; Bian, Shaoquan; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

    2012-01-01

    Porous collagen scaffold is integrated with surface activated PLLA nanoparticles fabricated by lyophilizing and crosslinking via EDC treatment. In order to prepare surface-modified PLLA nanoparticles, PLLA was firstly grafted with poly (acrylic acid) (PAA) through surface-initiated polymerization of acrylic acid. Nanoparticles of average diameter 316 nm and zeta potential −39.88 mV were obtained from the such-treated PLLA by dialysis method. Porous collagen scaffold were fabricated by mixing PLLA nanoparticles with collagen solution, freeze drying, and crosslinking with EDC. SEM observation revealed that nanoparticles were homogeneously dispersed in collagen matrix, forming interconnected porous structure with pore size ranging from 150 to 200 μm, irrespective of the amount of nanoparticles. The porosity of the scaffolds kept almost unchanged with the increment of the nanoparticles, whereas the mechanical property was obviously improved, and the degradation was effectively retarded. In vitro L929 mouse fibroblast cells seeding and culture studies revealed that cells infiltrated into the scaffolds and were distributed homogeneously. Compared with the pure collagen sponge, the number of cells in hybrid scaffolds greatly increased with the increment of incorporated nanoparticles. These results manifested that the surface-activated PLLA nanoparticles effectively reinforced the porous collagen scaffold and promoted the cells penetrating into the scaffold, and proliferation. PMID:22448137

  18. Antioxidative and antiinflammatory activities of quercetin-loaded silica nanoparticles.

    PubMed

    Lee, Ga Hyun; Lee, Sung June; Jeong, Sang Won; Kim, Hyun-Chul; Park, Ga Young; Lee, Se Geun; Choi, Jin Hyun

    2016-07-01

    Utilizing the biological activities of compounds by encapsulating natural components in stable nanoparticles is an important strategy for a variety of biomedical and healthcare applications. In this study, quercetin-loaded silica nanoparticles were synthesized using an oil-in-water microemulsion method, which is a suitable system for producing functional nanoparticles of controlled size and shape. The resulting quercetin-loaded silica nanoparticles were spherical, highly monodispersed, and stable in an aqueous system. Superoxide radical scavenging effects were found for the quercetin-loaded silica nanoparticles as well as free quercetin. The quercetin-loaded silica nanoparticles showed cell viability comparable to that of the controls. The amounts of proinflammatory cytokines produced by macrophages, such as interleukin 1 beta, interleukin 6, and tumor necrosis factor alpha, were reduced significantly for the quercetin-loaded silica nanoparticles. These results suggest that the antioxidative and antiinflammatory activities of quercetin are maintained after encapsulation in silica. Silica nanoparticles can be used for the effective and stable incorporation of biologically active natural components into composite biomaterials.

  19. Photochemically Synthesized Polyimides

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.; Tyson, Daniel S.

    2008-01-01

    An alternative to the conventional approach to synthesis of polyimides involves the use of single monomers that are amenable to photopolymerization. Heretofore, the synthesis of polyimides has involved multiple-monomer formulations and heating to temperatures that often exceed 250 C. The present alternative approach enables synthesis under relatively mild conditions that can include room temperature. The main disadvantages of the conventional approach are the following: Elevated production temperatures can lead to high production costs and can impart thermal stresses to the final products. If the proportions of the multiple monomeric ingredients in a given batch are not exactly correct, the molecular weight and other physical properties of the final material could be reduced from their optimum or desired values. To be useful in the alternative approach, a monomer must have a molecular structure tailored to exploit Diels-Alder trapping of a photochemically generated ortho-quinodimethane. (In a Diels-Alder reaction, a diene combines with a dienophile to form molecules that contain six-membered rings.) In particular, a suitable monomer (see figure) contains ortho-methylbenzophenone connected to a dienophile (in this case, a maleimide) through a generic spacer group. Irradiation with ultraviolet light gives rise to a photochemical intermediate the aforementioned ortho-quinodimethane from the ortho-methylbenzophenone. This group may react with the dienophile on another such monomer molecule to produce an oligomer that, in turn may react in a stepgrowth manner to produce a polyimide. This approach offers several advantages in addition to those mentioned above: The monomer can be stored for a long time because it remains unreactive until exposed to light. Because the monomer is the only active starting ingredient, there is no need for mixing, no concern for ensuring correct proportions of monomers, and the purity of the final product material is inherently high. The use

  20. Synthesis and antibacterial activity of silver nanoparticles with different sizes

    NASA Astrophysics Data System (ADS)

    Martínez-Castañón, G. A.; Niño-Martínez, N.; Martínez-Gutierrez, F.; Martínez-Mendoza, J. R.; Ruiz, Facundo

    2008-12-01

    Silver nanoparticles with different sizes (7, 29, and 89 nm mean values) were synthesized using gallic acid in an aqueous chemical reduction method. The nanoparticles were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and ultraviolet-visible (UV-Vis) absorption spectroscopy; the antibacterial activity was assessed using the standard microdilution method, determining the minimum inhibitory concentration (MIC) according to the National Committee for Clinical Laboratory Standards. From the microscopies studies (TEM) we observed that silver nanoparticles have spherical (7 and 29 nm) and pseudospherical shape (89 nm) with a narrow size distribution. The sizes of the silver nanoparticles were controlled by varying some experimental conditions. It was found that the antibacterial activity of the nanoparticles varies when their size diminishes.

  1. Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity

    PubMed Central

    2012-01-01

    Polyhexamethylene biguanide (PHMB), a broad spectrum disinfectant against many pathogens, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles. The particles formed were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering, electrophoretic mobility, and TEM to measure their morphology and surface chemistry. PHMB-functionalized silver nanoparticles were then evaluated for their antimicrobial activity against a gram-negative bacterial strain, Escherichia coli. These silver nanoparticles were found to have about 100 times higher bacteriostatic and bactericidal activities, compared to the previous reports, due to the combined antibacterial effect of silver nanoparticles and PHMB. In addition to other applications, PHMB-functionalized silver nanoparticles would be extremely useful in textile industry due to the strong interaction of PHMB with cellulose fabrics. PMID:22625664

  2. Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Ashraf, Sumaira; Akhtar, Nasrin; Ghauri, Muhammad Afzal; Rajoka, Muhammad Ibrahim; Khalid, Zafar M.; Hussain, Irshad

    2012-05-01

    Polyhexamethylene biguanide (PHMB), a broad spectrum disinfectant against many pathogens, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles. The particles formed were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering, electrophoretic mobility, and TEM to measure their morphology and surface chemistry. PHMB-functionalized silver nanoparticles were then evaluated for their antimicrobial activity against a gram-negative bacterial strain, Escherichia coli. These silver nanoparticles were found to have about 100 times higher bacteriostatic and bactericidal activities, compared to the previous reports, due to the combined antibacterial effect of silver nanoparticles and PHMB. In addition to other applications, PHMB-functionalized silver nanoparticles would be extremely useful in textile industry due to the strong interaction of PHMB with cellulose fabrics.

  3. High-performance rechargeable batteries with nanoparticle active materials, photochemically regenerable active materials, and fast solid-state ion conductors

    DOEpatents

    Farmer, Joseph C.

    2017-04-04

    A high-performance rechargeable battery using ultra-fast ion conductors. In one embodiment the rechargeable battery apparatus includes an enclosure, a first electrode operatively connected to the enclosure, a second electrode operatively connected to the enclosure, a nanomaterial in the enclosure, and a heat transfer unit.

  4. Study of the antibacterial activity of ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Surti, Arjuman; Radha, S.; Garje, S. S.

    2013-02-01

    This study focuses on the antibacterial activity of the ZnO nanoparticles against organisms causing skin and wound infections. The nanoparticles were synthesized by a wet chemical route. The method was quick and nanoparticles were obtained in 3 days of incubation in dark. Characterization of the nanoparticles was done by X-Ray Diffraction and UV-Visible Spectrophotometry. It was observed that the UV-Visible spectrum peak was obtained at 357 nm corresponding to the Plasmon absorbance of Zinc oxide. X-Ray diffraction exhibited the 2θ values corresponding to Zinc oxide and the particle size was estimated to be 20 nm. The antibacterial effect of nanoparticles was observed against Staphylococcus spp and Bacillus spp. The significance of the bactericidal activity of the nanoparticles lies in the reduction of using antibiotics against nosocomial infections, especially in prolonged treatments. The bandage material used in wound dressing was coated with ZnO nanoparticles by adsorption method. The textile was found to be efficient in inhibiting the growth of these organisms. The effect of adverse storage conditions on the coated bandage material was also studied. On comparing the results obtained at extreme pH and temperature and those obtained at optimum conditions, it was seen that the nanoparticles were less effective at these extreme conditions.

  5. Size Effects in the Catalytic Activity of Unsupported Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Weber, Alfred P.; Seipenbusch, Martin; Kasper, Gerhard

    2003-08-01

    The influence of the size of nanoparticles on their catalytic activity was investigated for two systems on unsupported, i.e. gasborne nanoparticles. For the oxidation of hydrogen on Pt nanoparticle agglomerates, transport processes had to be taken into account to extract the real nanoparticle size effects. The results indicate an optimum particle size for the catalytic activity below 5nm which points clearly toward a real volume effect. In the case of the methanation reaction on gasborne Ni nanoparticles, no transport limitations were observed and the product concentration was directly proportional to the activity of the primary particles. We found an activity maximum for particles of about 19nm in diameter. This size is too large to be attributed to a real nanoparticle size effect induced by the electronic band structure. Therefore, we concluded that the particle size influences the adsorption behavior of the carbon monoxide molecules. In fact, it is known that intermediate adsorption enthalpies may favor dissociation processes, which is an essential step for the reaction, as manifested in the so called volcano-shaped curve. Then, in addition to the material dependence of the adsorption, we would also encounter a direct size dependence in the case of methanation on gasborne Ni nanoparticles.

  6. [Murine peritoneal neutrophil activation upon tungsten nanoparticles exposure in vivo].

    PubMed

    Martinova, E A; Baranov, V I

    2014-01-01

    Two examples of tungsten carbide nanoparticles (d = 15 nm, 50 nm) and tungsten carbide nanoparticles with 8% cobalt (d = 50 nm) have been found to induce the neutrophil activation 3 h and 36 h after intraperitoneal administration in the doses 0.005; 0.025; 0.05; 0.25; 0.5; 1; 2.5 and 5 microgram per 1 gram body weight to FVB mice. Neutrophil activation was calculated based on the CD11b and S100 antigen expression. Effect of nanoparticles is bimodal for all tested examples.

  7. Iodide-induced organothiol desorption and photochemical reaction, gold nanoparticle (AuNP) fusion, and SERS signal reduction in organothiol-containing AuNP aggregates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gold nanoparticles (AuNPs) have been used extensively as surface-enhanced Raman spectroscopic (SERS) substrates for their large SERS enhancements and widely believed chemical stability. Presented is the finding that iodide can rapidly reduce the SERS intensity of the ligands, including organothiols ...

  8. Intrinsic peroxidase-like activity of ferromagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Gao, Lizeng; Zhuang, Jie; Nie, Leng; Zhang, Jinbin; Zhang, Yu; Gu, Ning; Wang, Taihong; Feng, Jing; Yang, Dongling; Perrett, Sarah; Yan, Xiyun

    2007-09-01

    Nanoparticles containing magnetic materials, such as magnetite (Fe3O4), are particularly useful for imaging and separation techniques. As these nanoparticles are generally considered to be biologically and chemically inert, they are typically coated with metal catalysts, antibodies or enzymes to increase their functionality as separation agents. Here, we report that magnetite nanoparticles in fact possess an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, which are widely used to oxidize organic substrates in the treatment of wastewater or as detection tools. Based on this finding, we have developed a novel immunoassay in which antibody-modified magnetite nanoparticles provide three functions: capture, separation and detection. The stability, ease of production and versatility of these nanoparticles makes them a powerful tool for a wide range of potential applications in medicine, biotechnology and environmental chemistry.

  9. Spectroscopy and photocatalytic activity of tetracene nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Hee-Young; Bjorklund, Thomas; Lim, Sang-Hyun; Bardeen, Christopher

    2003-03-01

    Tetracene nanoparticles are synthesized using a reprecipitation technique to form a suspension in wateer. The nanoparticles are plate-like and have a broad size distribution, centered at around 50 nm in diameter as measured using AFM. The optical spectroscopy is similar to what is observed in polycrystalline tetracene films, so the tetracene is not chemically modified even in water. The chemical stability of tetracene nanoparticles in solution is enhanced by roughly one order of magnitude as compared to monomeric tetracene. Under visible illumination, these nanoparticles catalyze the destruction of various organic molecules in water. The reaction does not depend on the presence of oxygen, and the kinetics are consistent with a heterogeneous reaction mechanism where the molecules adsorb onto the surface of the particle and undergo photo-oxidation. The high surface-to-volume ratio of these particles may provide an efficient way to transform absorbed photons into chemically reactive surface states.

  10. Photochemical functionalization of diamond surfaces

    NASA Astrophysics Data System (ADS)

    Nichols, Beth Marie

    Diamond surfaces are excellent substrates for potential applications in fields such as biotechnology, molecular sensing, and molecular electronics. In order to develop new diamond-based technologies, it is important to develop a fundamental understanding of diamond surface chemistry. Previous work in the Hamers group has demonstrated covalent functionalization of hydrogen-terminated diamond surfaces with molecules bearing a terminal vinyl group via a photochemical process using sub-bandgap light at 254 nm. While the reaction was shown to occur reproducibly with self-terminating monolayer surface coverage, the mechanism was never fully understood. This thesis investigates the photochemical modification of hydrogen-terminated surfaces of diamond. The results show that this reaction is a surface-mediated radical process initiated by the UV-assisted photoejection of electrons from the diamond surfaces into the liquid phase. To develop a better understanding of the photochemical mechanism, an electrical bias was applied to the diamond samples during the photochemical reaction. Applying a 1 volt potential between two diamond electrodes significantly increases the rate of functionalization of the negative electrode. Cyclic voltammetry and electrochemical impedance measurements show that the applied potential induces downward band-bending within the negative diamond film electrode. At higher voltages a Faradaic current is observed, with no further acceleration of the functionalization rate. The bias-dependent changes in rate are attributed to a field effect; the applied potential induces a downward band-bending on the negative electrode and facilitates electron ejection into the adjacent organic fluid. The ability to directly organically photopattern the surface on length scales of <25 microns has also been demonstrated using simple photomasking techniques. Techniques for the functionalization of diamond may be applied to other 'unreactive' surfaces. The activation of a

  11. Preparation and bactericide activity of gallic acid stabilized gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Moreno-Álvarez, S. A.; Martínez-Castañón, G. A.; Niño-Martínez, N.; Reyes-Macías, J. F.; Patiño-Marín, N.; Loyola-Rodríguez, J. P.; Ruiz, Facundo

    2010-10-01

    In this work, gold nanoparticles with three different sizes (13.7, 39.4, and 76.7 nm) were prepared using a simple aqueous method with gallic acid as the reducing and stabilizing agent, the different sizes were obtained varying some experimental parameters as the pH of the reaction and the amount of the gallic acid. The prepared nanoparticles were characterized using X-ray diffraction, transmission electron microscopy, dynamic light scattering, and UV-Vis spectroscopy. Samples were identified as elemental gold and present spherical morphology, a narrow size distribution and good stabilization according to TEM and DLS results. The antibacterial activity of this gallic acid stabilized gold nanoparticles against S. mutans (the etiologic agent of dental caries) was assessed using a microdilution method obtaining a minimum inhibitory concentration of 12.31, 12.31, and 49.25 μg/mL for 13.7, 39.4, and 76.7 nm gold nanoparticles, respectively. The antibacterial assay showed that gold nanoparticles prepared in this work present a bactericide activity by a synergistic action with gallic acid. The MIC found for this nanoparticles are much lower than those reported for mixtures of gold nanoparticles and antibiotics.

  12. Catalytically and biologically active silver nanoparticles synthesized using essential oil

    NASA Astrophysics Data System (ADS)

    Vilas, Vidya; Philip, Daizy; Mathew, Joseph

    2014-11-01

    There are numerous reports on phytosynthesis of silver nanoparticles and various phytochemicals are involved in the reduction and stabilization. Pure explicit phytosynthetic protocol for catalytically and biologically active silver nanoparticles is of importance as it is an environmentally benign green method. This paper reports the use of essential oil of Myristica fragrans enriched in terpenes and phenyl propenes in the reduction and stabilization. FTIR spectra of the essential oil and the synthesized biogenic silver nanoparticles are in accordance with the GC-MS spectral analysis reports. Nanosilver is initially characterized by an intense SPR band around 420 nm, followed by XRD and TEM analysis revealing the formation of 12-26 nm sized, highly pure, crystalline silver nanoparticles. Excellent catalytic and bioactive potential of the silver nanoparticles is due to the surface modification. The chemocatalytic potential of nanosilver is exhibited by the rapid reduction of the organic pollutant, para nitro phenol and by the degradation of the thiazine dye, methylene blue. Significant antibacterial activity of the silver colloid against Gram positive, Staphylococcus aureus (inhibition zone - 12 mm) and Gram negative, Escherichia coli (inhibition zone - 14 mm) is demonstrated by Agar-well diffusion method. Strong antioxidant activity of the biogenic silver nanoparticles is depicted through NO scavenging, hydrogen peroxide scavenging, reducing power, DPPH and total antioxidant activity assays.

  13. Synthesis and antibacterial activity of of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Maliszewska, I.; Sadowski, Z.

    2009-01-01

    Silver nanoparticles have been known to have inhibitory and bactericidal effects but the antimicrobial mechanism have not been clearly revealed. Here, we report on the synthesis of metallic nanoparticles of silver using wild strains of Penicillium isolated from environment. Kinetics of the formation of nanosilver was monitored using the UV-Vis. TEM micrographs showed the formation of silver nanoparticles in the range 10-100 nm. Obtained Ag nanoparticles were evaluated for their antimicrobial activity against the gram-positive and gram-negative bacteria. As results, Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were effectively inhibited. Nanosilver is a promising candidate for development of future antibacterial therapies because of its wide spectrum of activity.

  14. Photochemical tissue bonding

    DOEpatents

    Redmond, Robert W [Brookline, MA; Kochevar, Irene E [Charlestown, MA

    2012-01-10

    Photochemical tissue bonding methods include the application of a photosensitizer to a tissue and/or tissue graft, followed by irradiation with electromagnetic energy to produce a tissue seal. The methods are useful for tissue adhesion, such as in wound closure, tissue grafting, skin grafting, musculoskeletal tissue repair, ligament or tendon repair and corneal repair.

  15. Evaluation of Hemagglutination Activity of Chitosan Nanoparticles Using Human Erythrocytes

    PubMed Central

    de Lima, Jefferson Muniz; Sarmento, Ronaldo Rodrigues; de Souza, Joelma Rodrigues; Brayner, Fábio André; Feitosa, Ana Paula Sampaio; Padilha, Rafael; Alves, Luiz Carlos; Porto, Isaque Jerônimo; Batista, Roberta Ferreti Bonan Dantas; de Oliveira, Juliano Elvis; de Medeiros, Eliton Souto; Bonan, Paulo Rogério Ferreti; Castellano, Lúcio Roberto

    2015-01-01

    Chitosan is a polysaccharide composed of randomly distributed chains of β-(1-4) D-glucosamine and N-acetyl-D-glucosamine. This compound is obtained by partial or total deacetylation of chitin in acidic solution. The chitosan-based hemostatic agents have been gaining much attention in the management of bleeding. The aim of this study was to evaluate in vitro hemagglutination activity of chitosan nanoparticles using human erythrocytes. The preparation of nanoparticles was achieved by ionotropic gelification technique followed by neutralization with NaOH 1 mol/L−1. The hemagglutination activity was performed on a solution of 2% erythrocytes (pH 7.4 on PBS) collected from five healthy volunteers. The hemolysis determination was made by spectrophotometric analysis. Chitosan nanoparticle solutions without NaOH addition changed the reddish colour of the wells into brown, suggesting an oxidative reaction of hemoglobin and possible cell lysis. All neutralized solutions of chitosan nanoparticles presented positive haemagglutination, without any change in reaction color. Chitosan nanoparticles presented hemolytic activity ranging from 186.20 to 223.12%, while neutralized solutions ranged from 2.56 to 72.54%, comparing to distilled water. Results highlight the need for development of new routes of synthesis of chitosan nanoparticles within human physiologic pH. PMID:25759815

  16. Evaluation of hemagglutination activity of chitosan nanoparticles using human erythrocytes.

    PubMed

    de Lima, Jefferson Muniz; Sarmento, Ronaldo Rodrigues; de Souza, Joelma Rodrigues; Brayner, Fábio André; Feitosa, Ana Paula Sampaio; Padilha, Rafael; Alves, Luiz Carlos; Porto, Isaque Jerônimo; Batista, Roberta Ferreti Bonan Dantas; de Oliveira, Juliano Elvis; de Medeiros, Eliton Souto; Bonan, Paulo Rogério Ferreti; Castellano, Lúcio Roberto

    2015-01-01

    Chitosan is a polysaccharide composed of randomly distributed chains of β-(1-4) D-glucosamine and N-acetyl-D-glucosamine. This compound is obtained by partial or total deacetylation of chitin in acidic solution. The chitosan-based hemostatic agents have been gaining much attention in the management of bleeding. The aim of this study was to evaluate in vitro hemagglutination activity of chitosan nanoparticles using human erythrocytes. The preparation of nanoparticles was achieved by ionotropic gelification technique followed by neutralization with NaOH 1 mol/L(-1). The hemagglutination activity was performed on a solution of 2% erythrocytes (pH 7.4 on PBS) collected from five healthy volunteers. The hemolysis determination was made by spectrophotometric analysis. Chitosan nanoparticle solutions without NaOH addition changed the reddish colour of the wells into brown, suggesting an oxidative reaction of hemoglobin and possible cell lysis. All neutralized solutions of chitosan nanoparticles presented positive haemagglutination, without any change in reaction color. Chitosan nanoparticles presented hemolytic activity ranging from 186.20 to 223.12%, while neutralized solutions ranged from 2.56 to 72.54%, comparing to distilled water. Results highlight the need for development of new routes of synthesis of chitosan nanoparticles within human physiologic pH.

  17. Eco-friendly approach for nanoparticles synthesis and mechanism behind antibacterial activity of silver and anticancer activity of gold nanoparticles.

    PubMed

    Patil, Maheshkumar Prakash; Kim, Gun-Do

    2017-01-01

    This review covers general information about the eco-friendly process for the synthesis of silver nanoparticles (AgNP) and gold nanoparticles (AuNP) and focuses on mechanism of the antibacterial activity of AgNPs and the anticancer activity of AuNPs. Biomolecules in the plant extract are involved in reduction of metal ions to nanoparticle in a one-step and eco-friendly synthesis process. Natural plant extracts contain wide range of metabolites including carbohydrates, alkaloids, terpenoids, phenolic compounds, and enzymes. A variety of plant species and plant parts have been successfully extracted and utilized for AgNP and AuNP syntheses. Green-synthesized nanoparticles eliminate the need for a stabilizing and capping agent and show shape and size-dependent biological activities. Here, we describe some of the plant extracts involved in nanoparticle synthesis, characterization methods, and biological applications. Nanoparticles are important in the field of pharmaceuticals for their strong antibacterial and anticancer activity. Considering the importance and uniqueness of this concept, the synthesis, characterization, and application of AgNPs and AuNPs are discussed in this review.

  18. Promotion of nano-anatase TiO(2) on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach.

    PubMed

    Su, Mingyu; Liu, Huiting; Liu, Chao; Qu, Chunxiang; Zheng, Lei; Hong, Fashui

    2009-06-01

    Previous researches approved that photocatalysis activity of nano-TiO(2) could obviously increase photosynthetic effects of spinach, but the mechanism of improving light energy transfer and conversion is still unclear. In the present we investigated effects of nano-anatase TiO(2) on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach. Several effects of nano-anatase TiO(2) were observed: (1) UV-vis spectrum was blue shifted in both Soret and Q bands, and the absorption intensity was obviously increased; (2) resonance Raman spectrum showed four main peaks, which are ascribed to carotene, and the Raman peak intensity was as 6.98 times as that of the control; (3) the fluorescence emission peak was blue shifted and the intensity was decreased by 23.59%; (4) the DCPIP photoreduction activity showed 129.24% enhancement; (5) the oxygen-evolving rate of PS II was elevated by 51.89%. Taken together, the studies of the experiments showed that nano-anatase TiO(2) had bound to D1/D2/Cyt b559 complex, promoted the spectral responses, leading to the improvement of primary electron separation, electron transfer and light energy conversion of D1/D2/Cyt b559 complex.

  19. Promotion of nano-anatase TiO 2 on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach

    NASA Astrophysics Data System (ADS)

    Su, Mingyu; Liu, Huiting; Liu, Chao; Qu, Chunxiang; Zheng, Lei; Hong, Fashui

    2009-06-01

    Previous researches approved that photocatalysis activity of nano-TiO 2 could obviously increase photosynthetic effects of spinach, but the mechanism of improving light energy transfer and conversion is still unclear. In the present we investigated effects of nano-anatase TiO 2 on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach. Several effects of nano-anatase TiO 2 were observed: (1) UV-vis spectrum was blue shifted in both Soret and Q bands, and the absorption intensity was obviously increased; (2) resonance Raman spectrum showed four main peaks, which are ascribed to carotene, and the Raman peak intensity was as 6.98 times as that of the control; (3) the fluorescence emission peak was blue shifted and the intensity was decreased by 23.59%; (4) the DCPIP photoreduction activity showed 129.24% enhancement; (5) the oxygen-evolving rate of PS II was elevated by 51.89%. Taken together, the studies of the experiments showed that nano-anatase TiO 2 had bound to D1/D2/Cyt b559 complex, promoted the spectral responses, leading to the improvement of primary electron separation, electron transfer and light energy conversion of D1/D2/Cyt b559 complex.

  20. Antibacterial Activity of Polymer Coated Cerium Oxide Nanoparticles

    PubMed Central

    Shah, Vishal; Shah, Shreya; Shah, Hirsh; Rispoli, Fred J.; McDonnell, Kevin T.; Workeneh, Selam; Karakoti, Ajay; Kumar, Amit; Seal, Sudipta

    2012-01-01

    Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO4, CaCl2, KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to understand the collective influence of the tested parameters on the anti-bacterial activity and subsequently a computer-based, interactive visualization tool was developed. The visualization allows us to elucidate the effect of each of the parameters in combination with other parameters, on the antibacterial activity of nanoparticles. The results indicate that the toxicity of CeO2 NPs depend on the physical and chemical environment; and in a majority of the possible combinations of the nine parameters, non-lethal to the bacteria. In fact, the cerium oxide nanoparticles can decrease the anti-bacterial activity exerted by magnesium and potassium salts. PMID:23110109

  1. Photochemical studies and nanomolar photodynamic activities of phthalocyanines functionalized with 1,4,7-trioxanonyl moieties at their non-peripheral positions.

    PubMed

    Sobotta, Lukasz; Wierzchowski, Marcin; Mierzwicki, Michal; Gdaniec, Zofia; Mielcarek, Jadwiga; Persoons, Leentje; Goslinski, Tomasz; Balzarini, Jan

    2016-02-01

    Manganese(III), cobalt(II), copper(II), magnesium(II), zinc(II) and metal-free phthalocyanines, possessing 1,4,7-trioxanonyl substituents, at their non-peripheral positions, were subjected to photochemical, photodynamic and biological activity studies. Demetallated phthalocyanine and its metallated d-block analogues, with copper(II), cobalt(II), manganese(III) chloride, were found to be less efficient singlet oxygen generators in comparison to the zinc(II) analogue and zinc(II) phthalocyanine reference. Irradiation of several phthalocyanines for short time periods resulted in a substantially increased cytostatic activity against both suspension (leukemic/lymphoma at 85nM) and solid (cervix carcinoma at 72nM and melanoma at 81nM) tumour cell lines (up to 200-fold). Noteworthy is that enveloped viruses, such as for herpesvirus and influenza A virus, but not, non-enveloped virus strains, such as Coxsackie B4 virus and reovirus-1, exposed to irradiation in the presence of the phthalocyanines, markedly lost their infectivity potential.

  2. Photochemical isotope separation

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

    1987-01-01

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  3. Antimicrobial activity of bone cements embedded with organic nanoparticles.

    PubMed

    Perni, Stefano; Thenault, Victorien; Abdo, Pauline; Margulis, Katrin; Magdassi, Shlomo; Prokopovich, Polina

    2015-01-01

    Infections after orthopedic surgery are a very unwelcome outcome; despite the widespread use of antibiotics, their incidence can be as high as 10%. This risk is likely to increase as antibiotics are gradually losing efficacy as a result of bacterial resistance; therefore, novel antimicrobial approaches are required. Parabens are a class of compounds whose antimicrobial activity is employed in many cosmetic and pharmaceutical products. We developed propylparaben nanoparticles that are hydrophilic, thus expanding the applicability of parabens to aqueous systems. In this paper we assess the possibility of employing paraben nanoparticles as antimicrobial compound in bone cements. The nanoparticles were embedded in various types of bone cement (poly(methyl methacrylate) [PMMA], hydroxyapatite, and brushite) and the antimicrobial activity was determined against common causes of postorthopedic surgery infections such as: Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, and Acinetobacter baumannii. Nanoparticles at concentrations as low as 1% w/w in brushite bone cement were capable of preventing pathogens growth, 5% w/w was needed for hydroxyapatite bone cement, while 7% w/w was required for PMMA bone cement. No detrimental effect was determined by the addition of paraben nanoparticles on bone cement compression strength and cytocompatibility. Our results demonstrate that paraben nanoparticles can be encapsulated in bone cement, providing concentration-dependent antimicrobial activity; furthermore, lower concentrations are needed in calcium phosphate (brushite and hydroxyapatite) than in acrylic (PMMA) bone cements. These nanoparticles are effective against a wide spectrum of bacteria, including those already resistant to the antibiotics routinely employed in orthopedic applications, such as gentamicin.

  4. Antimicrobial activity of bone cements embedded with organic nanoparticles

    PubMed Central

    Perni, Stefano; Thenault, Victorien; Abdo, Pauline; Margulis, Katrin; Magdassi, Shlomo; Prokopovich, Polina

    2015-01-01

    Infections after orthopedic surgery are a very unwelcome outcome; despite the widespread use of antibiotics, their incidence can be as high as 10%. This risk is likely to increase as antibiotics are gradually losing efficacy as a result of bacterial resistance; therefore, novel antimicrobial approaches are required. Parabens are a class of compounds whose antimicrobial activity is employed in many cosmetic and pharmaceutical products. We developed propylparaben nanoparticles that are hydrophilic, thus expanding the applicability of parabens to aqueous systems. In this paper we assess the possibility of employing paraben nanoparticles as antimicrobial compound in bone cements. The nanoparticles were embedded in various types of bone cement (poly(methyl methacrylate) [PMMA], hydroxyapatite, and brushite) and the antimicrobial activity was determined against common causes of postorthopedic surgery infections such as: Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, and Acinetobacter baumannii. Nanoparticles at concentrations as low as 1% w/w in brushite bone cement were capable of preventing pathogens growth, 5% w/w was needed for hydroxyapatite bone cement, while 7% w/w was required for PMMA bone cement. No detrimental effect was determined by the addition of paraben nanoparticles on bone cement compression strength and cytocompatibility. Our results demonstrate that paraben nanoparticles can be encapsulated in bone cement, providing concentration-dependent antimicrobial activity; furthermore, lower concentrations are needed in calcium phosphate (brushite and hydroxyapatite) than in acrylic (PMMA) bone cements. These nanoparticles are effective against a wide spectrum of bacteria, including those already resistant to the antibiotics routinely employed in orthopedic applications, such as gentamicin. PMID:26487803

  5. Resveratrol-loaded Nanoparticles Induce Antioxidant Activity against Oxidative Stress

    PubMed Central

    Kim, Jae-Hwan; Park, Eun-Young; Ha, Ho-Kyung; Jo, Chan-Mi; Lee, Won-Jae; Lee, Sung Sill; Kim, Jin Wook

    2016-01-01

    Resveratrol acts as a free radical scavenger and a potent antioxidant in the inhibition of numerous reactive oxygen species (ROS). The function of resveratrol and resveratrol-loaded nanoparticles in protecting human lung cancer cells (A549) against hydrogen peroxide was investigated in this study. The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay was performed to evaluate the antioxidant properties. Resveratrol had substantially high antioxidant capacity (trolox equivalent antioxidant capacity value) compared to trolox and vitamin E since the concentration of resveratrol was more than 50 μM. Nanoparticles prepared from β-lactoglobulin (β-lg) were successfully developed. The β-lg nanoparticle showed 60 to 146 nm diameter in size with negatively charged surface. Non-cytotoxicity was observed in Caco-2 cells treated with β-lg nanoparticles. Fluorescein isothiocynate-conjugated β-lg nanoparticles were identified into the cell membrane of Caco-2 cells, indicating that nanoparticles can be used as a delivery system. Hydrogen peroxide caused accumulation of ROS in a dose- and time-dependent manner. Resveratrol-loaded nanoparticles restored H2O2-induced ROS levels by induction of cellular uptake of resveratrol in A549 cells. Furthermore, resveratrol activated nuclear factor erythroid 2-related factor 2-Kelch ECH associating protein 1 (Nrf2-Keap1) signaling in A549 cells, thereby accumulation of Nrf2 abundance, as demonstrated by western blotting approach. Overall, these results may have implications for improvement of oxidative stress in treatment with nanoparticles as a biodegradable and non-toxic delivery carrier of bioactive compounds. PMID:26732454

  6. Functional Nanoparticles Activate a Decellularized Liver Scaffold for Blood Detoxification.

    PubMed

    Xu, Fen; Kang, Tianyi; Deng, Jie; Liu, Junli; Chen, Xiaolei; Wang, Yuan; Ouyang, Liang; Du, Ting; Tang, Hong; Xu, Xiaoping; Chen, Shaochen; Du, Yanan; Shi, Yujun; Qian, Zhiyong; Wei, Yuquan; Deng, Hongxin; Gou, Maling

    2016-04-01

    Extracorporeal devices have great promise for cleansing the body of virulence factors that are caused by venomous injuries, bacterial infections, and biological weaponry. The clinically used extracorporeal devices, such as artificial liver-support systems that are mainly based on dialysis or electrostatic interaction, are limited to remove a target toxin. Here, a liver-mimetic device is shown that consists of decellularized liver scaffold (DLS) populated with polydiacetylene (PDA) nanoparticles. DLS has the gross shape and 3D architecture of a liver, and the PDA nanoparticles selectively capture and neutralize the pore-forming toxins (PFTs). This device can efficiently and target-orientedly remove PFTs in human blood ex vivo without changing blood components or activating complement factors, showing potential application in antidotal therapy. This work provides a proof-of-principle for blood detoxification by a nanoparticle-activated DLS, and can lead to the development of future medical devices for antidotal therapy.

  7. Novel strategies for ultrahigh specific activity targeted nanoparticles

    SciTech Connect

    Zhou, Dong

    2012-12-13

    We have developed novel strategies optimized for preparing high specific activity radiolabeled nanoparticles, targeting nuclear imaging of low abundance biomarkers. Several compounds have been labeled with F-18 and Cu-64 for radiolabeling of SCK-nanoparticles via Copper(I) catalyzed or copper-free alkyne-azide cyclolization. Novel strategies have been developed to achieve ultrahigh specific activity with administrable amount of dose for human study using copper-free chemistry. Ligands for carbonic anhydrase 12 (CA12), a low abundance extracellular biomarker for the responsiveness of breast cancer to endocrine therapie, have been labeled with F-18 and Cu-64, and one of them has been evaluated in animal models. The results of this project will lead to major improvements in the use of nanoparticles in nuclear imaging and will significantly advance their potential for detecting low abundance biomarkers of medical importance.

  8. Influence of Temperature on the Formation of Silver Nanoparticles by using a Seed-Free Photochemical Method under Sodium-Lamp Irradiation.

    PubMed

    Kuo, Yen-Ling; Juang, Tzong-Yuan; Chang, Shi-Hise; Tsai, Chin-Ming; Lai, Yen-Shang; Yang, Li-Chen; Huang, Cheng-Liang

    2015-10-26

    Silver nanoparticles can be prepared by using a seed-free photo-assisted citrate reduction method under the irradiation of a sodium lamp. Under the same irradiation intensity, bath temperatures are crucial in influencing the reaction rate, morphologies of final products, and shape evolution of the silver nanostructures. For example, when the bath temperature is 80 °C, the product yields of silver nanoplates, nanorods, and nanodecahedra are 38±6 %, 35±10 %, and 12±8 %, respectively. However, when the bath temperature is 30 °C, the product yields of silver nanoplates, nanorods, and nanodecahedra are 6±3 %, 0 %, and 83±16 %, respectively. Time-dependent UV/Vis spectra and TEM images show that silver nanoplates were formed at the earlier reaction stage and greatly decreased in amount at the later stage when the bath temperatures are less than or equal to 40 °C. This indicates that the silver nanoplates, which can be regarded as intermediates, are kinetically favored products. They are not thermodynamically favored products at these relatively low bath temperatures. The SERS spectra of crystal violet (CV) show that all the silver colloids synthesized at various temperatures exhibit good enhancement factors and that the colloids prepared at lower bath temperatures have a higher enhancement factor.

  9. Antimicrobial activity of the metals and metal oxide nanoparticles.

    PubMed

    Dizaj, Solmaz Maleki; Lotfipour, Farzaneh; Barzegar-Jalali, Mohammad; Zarrintan, Mohammad Hossein; Adibkia, Khosro

    2014-11-01

    The ever increasing resistance of pathogens towards antibiotics has caused serious health problems in the recent years. It has been shown that by combining modern technologies such as nanotechnology and material science with intrinsic antimicrobial activity of the metals, novel applications for these substances could be identified. According to the reports, metal and metal oxide nanoparticles represent a group of materials which were investigated in respect to their antimicrobial effects. In the present review, we focused on the recent research works concerning antimicrobial activity of metal and metal oxide nanoparticles together with their mechanism of action. Reviewed literature indicated that the particle size was the essential parameter which determined the antimicrobial effectiveness of the metal nanoparticles. Combination therapy with the metal nanoparticles might be one of the possible strategies to overcome the current bacterial resistance to the antibacterial agents. However, further studies should be performed to minimize the toxicity of metal and metal oxide nanoparticles to apply as proper alternatives for antibiotics and disinfectants especially in biomedical applications.

  10. Multiple strategies to activate gold nanoparticles as antibiotics

    NASA Astrophysics Data System (ADS)

    Zhao, Yuyun; Jiang, Xingyu

    2013-08-01

    Widespread antibiotic resistance calls for new strategies. Nanotechnology provides a chance to overcome antibiotic resistance by multiple antibiotic mechanisms. This paper reviews the progress in activating gold nanoparticles with nonantibiotic or antibiotic molecules to combat bacterial resistance, analyzes the gap between experimental achievements and real clinical application, and suggests some potential directions in developing antibacterial nanodrugs.

  11. Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro

    NASA Astrophysics Data System (ADS)

    Speshock, Janice L.; Braydich-Stolle, Laura K.; Szymanski, Eric R.; Hussain, Saber M.

    2011-12-01

    Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

  12. Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro.

    PubMed

    Speshock, Janice L; Braydich-Stolle, Laura K; Szymanski, Eric R; Hussain, Saber M

    2011-12-01

    Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

  13. Effect of TiO₂ nanoparticles on the structure and activity of catalase.

    PubMed

    Zhang, Hong-Mei; Cao, Jian; Tang, Bo-Ping; Wang, Yan-Qing

    2014-08-05

    TiO₂ nanoparticles are the most widely used metal oxide nanoparticles and have oxidative toxicity. Catalase is an important antioxidant enzyme. Here the understanding of an effect of TiO₂ nanoparticles on the activity and structure of catalase is crucial to characterize the toxicity of TiO₂ nanoparticles. These experimental data revealed that TiO₂ nanoparticles could bind to catalase by the electrostatic and hydrogen bonding forces. On binding TiO₂ nanoparticles, catalase got destabilized with the decrease of α-helices content, the solvent polarity of environment around the fluorescence chromophores on catalase were also affected. In addition, TiO₂ nanoparticles also affected the activity of catalase. TiO₂ nanoparticles acted as an activator of catalase activity at a low molar concentration and as an inhibitor at a higher molar concentration. With regard to human health, the present study could provide a better understanding of the potential nanotoxicity of TiO₂ nanoparticles.

  14. Photochemical cutting of fabrics

    DOEpatents

    Piltch, Martin S.

    1994-01-01

    Apparatus for the cutting of garment patterns from one or more layers of fabric. A laser capable of producing laser light at an ultraviolet wavelength is utilized to shine light through a pattern, such as a holographic phase filter, and through a lens onto the one or more layers of fabric. The ultraviolet laser light causes rapid photochemical decomposition of the one or more layers of fabric, but only along the pattern. The balance of the fabric of the one or more layers of fabric is undamaged.

  15. Asymmetric nanoparticle may go "active" at room temperature

    NASA Astrophysics Data System (ADS)

    Sheng, Nan; Tu, YuSong; Guo, Pan; Wan, RongZheng; Wang, ZuoWei; Fang, HaiPing

    2017-04-01

    Using molecular dynamics simulations, we show that an asymmetrically shaped nanoparticle in dilute solution possesses a spontaneously curved trajectory within a finite time interval, instead of the generally expected random walk. This unexpected dynamic behavior has a similarity to that of active matters, such as swimming bacteria, cells, or even fish, but is of a different physical origin. The key to the curved trajectory lies in the non-zero resultant force originated from the imbalance of the collision forces acted by surrounding solvent molecules on the asymmetrically shaped nanoparticle during its orientation regulation. Theoretical formulae based on microscopic observations have been derived to describe this non-zero force and the resulting motion of the asymmetrically shaped nanoparticle.

  16. Highly bacterial resistant silver nanoparticles: synthesis and antibacterial activities

    NASA Astrophysics Data System (ADS)

    Chudasama, Bhupendra; Vala, Anjana K.; Andhariya, Nidhi; Mehta, R. V.; Upadhyay, R. V.

    2010-06-01

    In this article, we describe a simple one-pot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO3 using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block co-polymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 ± 1.5 nm (σ = 18.3%) and 31.1 ± 4.5 nm (σ = 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive ( Bacillus megaterium and Staphylococcus aureus), and three Gram negative ( Escherichia coli, Proteus vulgaris and Shigella sonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.

  17. Antimicrobial Activities of Silver Nanoparticles Synthesized by Using Water Extract of Arnicae anthodium.

    PubMed

    Dobrucka, Renata; Długaszewska, Jolanta

    2015-06-01

    Green synthesis of nanoparticles has gained significant importance in recent years and has become the one of the most preferred methods. Also, green synthesis of nanoparticles is valuable branch of nanotechnology. Plant extracts are eco-friendly and can be an economic option for synthesis of nanoparticles. This study presents method the synthesis of silver nanoparticles using water extract of Arnicae anthodium. Formation of silver nanoparticles was confirmed by UV-visble spectroscopy, Fourier transform infrared spectroscopy and total reflection X-ray fluorescence analysis. The morphology of the synthesized silver nanoparticles was verified by SEM-EDS. The obtained silver nanoparticles were used to study their antimicrobial activity.

  18. Influence of gold nanoparticles on platelets functional activity in vitro

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Akchurin, George G.; Ivanov, Alexey N.; Kirichuk, Vyacheslav F.; Terentyuk, George S.; Khlebtsov, Boris N.; Khlebtsov, Nikolay G.

    2008-02-01

    Now in the leading biomedical centers of the world approved new technology of laser photothermal destruction of cancer cells using plasmon gold nanoparticles. Investigations of influence of gold nanoparticles on white rat platelets aggregative activity in vitro have been made. Platelet aggregation was investigated in platelet rich plasma (PRP) with help of laser analyzer 230 LA <>, Russia). Aggregation inductor was ADP solution in terminal concentration 2.5 micromole (<>, Russia). Gold nanoshells soluted in salt solution were used for experiments. Samples of PRP were incubated with 50 or 100 μl gold nanoshells solution in 5 minute, after that we made definition ADP induced platelet aggregation. We found out increase platelet function activity after incubation with nanoparticles solution which shown in maximum ADP-induced aggregation degree increase. Increase platelet function activity during intravenous nanoshells injection can be cause of thrombosis on patients. That's why before clinical application of cancer cell destruction based on laser photothermal used with plasmon gold nanoparticles careful investigations of thrombosis process and detail analyze of physiological blood parameters are very necessary.

  19. Monocatenary, branched, double-headed, and bolaform surface active carbohydrate esters via photochemical thiol-ene/-yne reactions.

    PubMed

    Boyère, Cédric; Broze, Guy; Blecker, Christophe; Jérôme, Christine; Debuigne, Antoine

    2013-10-18

    An original and versatile method for the synthesis of a range of novel mannose-based surfactants was developed via metal-free photo-induced thiol-ene/-yne 'click' reactions. This light-mediated hydrothiolation reaction involving a thiolated mannose was successfully applied to terminal and internal alkenes, dienes, and alkynes, leading to monocatenary, branched, double-headed, and bolaform amphiphilic carbohydrate esters, respectively. A surface activity study showed that these new compounds possess valuable properties and display specific behavior at the air-water interface. It also demonstrated the greater flexibility of the thioether moiety in the spacer of the surfactants produced via a thiol-ene reaction in comparison with the triazole heterocyclic rings in similar glucose-based surfactants synthesized elsewhere by the alkyne-azide 1,3-dipolar addition.

  20. Characterization and water activation behavior of tourmaline nanoparticles.

    PubMed

    Sun, S; Wei, C D; Liu, Y X

    2010-03-01

    Tourmaline nanoparticles were prepared by using a wet mechanochemisty method. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that the tourmaline grain size is in the range from tens of nanometers to several hundred nanometers. Through characterization by Fourier transform infrared spectroscope, it was found that the milled tourmaline had a better far infrared emitting performance due to the increase of radiation surface area. The structure change of liquid water clusters induced by the addition of tourmaline nanoparticles was observed by nuclear magnetic resonance (NMR). The results showed that the addition of tourmaline nanoparticles reduced the 17O NMR full width at half maximum intensity (FWHM) for treated water and the volume of water molecule clusters. The feature of activated water was enhanced with decreasing tourmaline nanoparticles size due to the cooperation of strong surface electric field and high far infrared emissivity. Moreover the activation time can be maintained at 480 h suggesting the potential application of tourmaline in wastewater treatment.

  1. From tunable core-shell nanoparticles to plasmonic drawbridges: Active control of nanoparticle optical properties

    PubMed Central

    Byers, Chad P.; Zhang, Hui; Swearer, Dayne F.; Yorulmaz, Mustafa; Hoener, Benjamin S.; Huang, Da; Hoggard, Anneli; Chang, Wei-Shun; Mulvaney, Paul; Ringe, Emilie; Halas, Naomi J.; Nordlander, Peter; Link, Stephan; Landes, Christy F.

    2015-01-01

    The optical properties of metallic nanoparticles are highly sensitive to interparticle distance, giving rise to dramatic but frequently irreversible color changes. By electrochemical modification of individual nanoparticles and nanoparticle pairs, we induced equally dramatic, yet reversible, changes in their optical properties. We achieved plasmon tuning by oxidation-reduction chemistry of Ag-AgCl shells on the surfaces of both individual and strongly coupled Au nanoparticle pairs, resulting in extreme but reversible changes in scattering line shape. We demonstrated reversible formation of the charge transfer plasmon mode by switching between capacitive and conductive electronic coupling mechanisms. Dynamic single-particle spectroelectrochemistry also gave an insight into the reaction kinetics and evolution of the charge transfer plasmon mode in an electrochemically tunable structure. Our study represents a highly useful approach to the precise tuning of the morphology of narrow interparticle gaps and will be of value for controlling and activating a range of properties such as extreme plasmon modulation, nanoscopic plasmon switching, and subnanometer tunable gap applications. PMID:26665175

  2. Mechanism of antibacterial activity of copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Chatterjee, Arijit Kumar; Chakraborty, Ruchira; Basu, Tarakdas

    2014-04-01

    In a previous communication, we reported a new method of synthesis of stable metallic copper nanoparticles (Cu-NPs), which had high potency for bacterial cell filamentation and cell killing. The present study deals with the mechanism of filament formation and antibacterial roles of Cu-NPs in E. coli cells. Our results demonstrate that NP-mediated dissipation of cell membrane potential was the probable reason for the formation of cell filaments. On the other hand, Cu-NPs were found to cause multiple toxic effects such as generation of reactive oxygen species, lipid peroxidation, protein oxidation and DNA degradation in E. coli cells. In vitro interaction between plasmid pUC19 DNA and Cu-NPs showed that the degradation of DNA was highly inhibited in the presence of the divalent metal ion chelator EDTA, which indicated a positive role of Cu2+ ions in the degradation process. Moreover, the fast destabilization, i.e. the reduction in size, of NPs in the presence of EDTA led us to propose that the nascent Cu ions liberated from the NP surface were responsible for higher reactivity of the Cu-NPs than the equivalent amount of its precursor CuCl2; the nascent ions were generated from the oxidation of metallic NPs when they were in the vicinity of agents, namely cells, biomolecules or medium components, to be reduced simultaneously.

  3. Mechanism of antibacterial activity of copper nanoparticles.

    PubMed

    Chatterjee, Arijit Kumar; Chakraborty, Ruchira; Basu, Tarakdas

    2014-04-04

    In a previous communication, we reported a new method of synthesis of stable metallic copper nanoparticles (Cu-NPs), which had high potency for bacterial cell filamentation and cell killing. The present study deals with the mechanism of filament formation and antibacterial roles of Cu-NPs in E. coli cells. Our results demonstrate that NP-mediated dissipation of cell membrane potential was the probable reason for the formation of cell filaments. On the other hand, Cu-NPs were found to cause multiple toxic effects such as generation of reactive oxygen species, lipid peroxidation, protein oxidation and DNA degradation in E. coli cells. In vitro interaction between plasmid pUC19 DNA and Cu-NPs showed that the degradation of DNA was highly inhibited in the presence of the divalent metal ion chelator EDTA, which indicated a positive role of Cu(2+) ions in the degradation process. Moreover, the fast destabilization, i.e. the reduction in size, of NPs in the presence of EDTA led us to propose that the nascent Cu ions liberated from the NP surface were responsible for higher reactivity of the Cu-NPs than the equivalent amount of its precursor CuCl2; the nascent ions were generated from the oxidation of metallic NPs when they were in the vicinity of agents, namely cells, biomolecules or medium components, to be reduced simultaneously.

  4. Photochemical and DFT studies on DNA-binding ability and antibacterial activity of lanthanum(III)-phenanthroline complex

    NASA Astrophysics Data System (ADS)

    Niroomand, Sona; Khorasani-Motlagh, Mozhgan; Noroozifar, Meissam; Jahani, Shohreh; Moodi, Asieh

    2017-02-01

    The binding of the lanthanum(III) complex containing 1,10-phenanthroline (phen), [La(phen)3Cl3·OH2], to DNA is investigated by absorption and emission methods. This complex shows absorption decreasing in a charge transfer band, and fluorescence decrement when it binds to DNA. Electronic absorption spectroscopy (UV-Vis), fluorescence spectra, iodide quenching experiments, salt effect and viscosity measurements, ethidium bromide (EB) competition test, circular dichroism (CD) spectra as well as variable temperature experiments indicate that the La(III) complex binds to fish salmon (FS) DNA, presumably via groove binding mode. The binding constants (Kb) of the La(III) complex with DNA is (2.55 ± 0.02) × 106 M-1. Furthermore, the binding site size, n, the Stern-Volmer constant KSV and thermodynamic parameters; enthalpy change (ΔH0) and entropy change (ΔS0) and Gibb's free energy (ΔG0), are calculated according to relevant fluorescent data and the Van't Hoff equation. The La(III) complex has been screened for its antibacterial activities by the disc diffusion method. Also, in order to supplement the experimental findings, DFT computation and NBO analysis are carried out.

  5. Photochemical Modulation of Ras-Mediated Signal Transduction using Caged Farnesyltransferase Inhibitors: Activation via One- and Two-Photon Excitation

    PubMed Central

    Abate-Pella, Daniel; Zeliadt, Nicholette A.; Ochocki, Joshua D.; Warmka, Janel K.; Dore, Timothy M.; Blank, David A.; Wattenberg, Elizabeth V.; Distefano, Mark D.

    2012-01-01

    The creation of caged molecules involves the attachment of protecting groups to biologically active compounds such as ligands, substrates, and drugs that can be removed under specific conditions. Photoremovable caging groups are the most common due to their ability to be removed with high spatial and temporal resolution. Here, the synthesis and photochemistry of a caged inhibitor of protein farnesyltransferase, Bhc-FTI, is described. The inhibitor was caged by alkylation of a critical thiol functional group with a Bhc moiety; while Bhc is well established as a protecting group for carboxylates and phosphates, it has not been extensively used to cage sulfhydryls. The resulting caged molecule, Bhc-FTI, can be photolyzed with UV light to release the inhibitor (FTI) that prevents Ras farnesylation, Ras membrane localization and downstream signaling. Finally, it is shown that Bhc-FTI can be uncaged by two-photon excitation to produce FTI at levels sufficient to inhibit Ras localization and alter cell morphology. Given the widespread involvement of Ras proteins in signal transduction pathways, this caged inhibitor should be useful in a plethora of studies. PMID:22492666

  6. Photochemical modulation of Ras-mediated signal transduction using caged farnesyltransferase inhibitors: activation by one- and two-photon excitation.

    PubMed

    Abate-Pella, Daniel; Zeliadt, Nicholette A; Ochocki, Joshua D; Warmka, Janel K; Dore, Timothy M; Blank, David A; Wattenberg, Elizabeth V; Distefano, Mark D

    2012-05-07

    The creation of caged molecules involves the attachment of protecting groups to biologically active compounds such as ligands, substrates and drugs that can be removed under specific conditions. Photoremovable caging groups are the most common due to their ability to be removed with high spatial and temporal resolution. Here, the synthesis and photochemistry of a caged inhibitor of protein farnesyltransferase is described. The inhibitor, FTI, was caged by alkylation of a critical thiol group with a bromohydroxycoumarin (Bhc) moiety. While Bhc is well established as a protecting group for carboxylates and phosphates, it has not been extensively used to cage sulfhydryl groups. The resulting caged molecule, Bhc-FTI, can be photolyzed with UV light to release the inhibitor that prevents Ras farnesylation, Ras membrane localization and downstream signaling. Finally, it is shown that Bhc-FTI can be uncaged by two-photon excitation to produce FTI at levels sufficient to inhibit Ras localization and alter cell morphology. Given the widespread involvement of Ras proteins in signal transduction pathways, this caged inhibitor should be useful in a plethora of studies.

  7. Locking covalent organic frameworks with hydrogen bonds: general and remarkable effects on crystalline structure, physical properties, and photochemical activity.

    PubMed

    Chen, Xiong; Addicoat, Matthew; Jin, Enquan; Zhai, Lipeng; Xu, Hong; Huang, Ning; Guo, Zhaoqi; Liu, Lili; Irle, Stephan; Jiang, Donglin

    2015-03-11

    A series of two-dimensional covalent organic frameworks (2D COFs) locked with intralayer hydrogen-bonding (H-bonding) interactions were synthesized. The H-bonding interaction sites were located on the edge units of the imine-linked tetragonal porphyrin COFs, and the contents of the H-bonding sites in the COFs were synthetically tuned using a three-component condensation system. The intralayer H-bonding interactions suppress the torsion of the edge units and lock the tetragonal sheets in a planar conformation. This planarization enhances the interlayer interactions and triggers extended π-cloud delocalization over the 2D sheets. Upon AA stacking, the resulting COFs with layered 2D sheets amplify these effects and strongly affect the physical properties of the material, including improving their crystallinity, enhancing their porosity, increasing their light-harvesting capability, reducing their band gap, and enhancing their photocatalytic activity toward the generation of singlet oxygen. These remarkable effects on the structure and properties of the material were observed for both freebase and metalloporphyin COFs. These results imply that exploration of supramolecular ensembles would open a new approach to the structural and functional design of COFs.

  8. Antifungal activity of silver nanoparticles obtained by green synthesis.

    PubMed

    Mallmann, Eduardo José J; Cunha, Francisco Afrânio; Castro, Bruno N M F; Maciel, Auberson Martins; Menezes, Everardo Albuquerque; Fechine, Pierre Basílio Almeida

    2015-01-01

    Silver nanoparticles (AgNPs) are metal structures at the nanoscale. AgNPs have exhibited antimicrobial activities against fungi and bacteria; however synthesis of AgNPs can generate toxic waste during the reaction process. Accordingly, new routes using non-toxic compounds have been researched. The proposal of the present study was to synthesize AgNPs using ribose as a reducing agent and sodium dodecyl sulfate (SDS) as a stabilizer. The antifungal activity of these particles against C. albicans and C. tropicalis was also evaluated. Stable nanoparticles 12.5 ± 4.9 nm (mean ± SD) in size were obtained, which showed high activity against Candida spp. and could represent an alternative for fungal infection treatment.

  9. ANTIFUNGAL ACTIVITY OF SILVER NANOPARTICLES OBTAINED BY GREEN SYNTHESIS

    PubMed Central

    MALLMANN, Eduardo José J.; CUNHA, Francisco Afrânio; CASTRO, Bruno N.M.F.; MACIEL, Auberson Martins; MENEZES, Everardo Albuquerque; FECHINE, Pierre Basílio Almeida

    2015-01-01

    Silver nanoparticles (AgNPs) are metal structures at the nanoscale. AgNPs have exhibited antimicrobial activities against fungi and bacteria; however synthesis of AgNPs can generate toxic waste during the reaction process. Accordingly, new routes using non-toxic compounds have been researched. The proposal of the present study was to synthesize AgNPs using ribose as a reducing agent and sodium dodecyl sulfate (SDS) as a stabilizer. The antifungal activity of these particles against C. albicans and C. tropicalis was also evaluated. Stable nanoparticles 12.5 ± 4.9 nm (mean ± SD) in size were obtained, which showed high activity against Candida spp. and could represent an alternative for fungal infection treatment. PMID:25923897

  10. Nanoparticle-mediated remote control of enzymatic activity.

    PubMed

    Knecht, Leslie D; Ali, Nur; Wei, Yinan; Hilt, J Zach; Daunert, Sylvia

    2012-10-23

    Nanomaterials have found numerous applications as tunable, remotely controlled platforms for drug delivery, hyperthermia cancer treatment, and various other biomedical applications. The basis for the interest lies in their unique properties achieved at the nanoscale that can be accessed via remote stimuli. These properties could then be exploited to simultaneously activate secondary systems that are not remotely actuatable. In this work, iron oxide nanoparticles are encapsulated in a bisacrylamide cross-linked polyacrylamide hydrogel network along with a model dehalogenase enzyme, L-2-HAD(ST). This thermophilic enzyme is activated at elevated temperatures and has been shown to have optimal activity at 70 °C. By exposing the Fe(3)O(4) nanoparticles to a remote stimulus, an alternating magnetic field (AMF), enhanced system heating can be achieved, thus remotely activating the enzyme. The internal heating of the nanocomposite hydrogel network in the AMF results in a 2-fold increase in enzymatic activity as compared to the same hydrogel heated externally in a water bath, suggesting that the internal heating of the nanoparticles is more efficient than the diffusion-limited heating of the water bath. This system may prove useful for remote actuation of biomedical and environmentally relevant enzymes and find applications in a variety of fields.

  11. Polyimides by photochemical cyclopolymerization

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor)

    2005-01-01

    The novel polyimides of this invention are derived from Diels-Alder cyclopolymerization of photochemically generated bisdienes with dienophiles, such as bismaleimides, trismaleimides and mixtures thereof with maleimide end-caps. Irradiation of one or more diketones produces two distinct hydroxy o-quinodimethane (photoenol) intermediates. These intermediates are trapped via Diels-Alder cycloaddition with appropriate dienophiles, e.g., bismaleimide and/or trismaleimides to give the corresponding polyimides in quantitative yields. When bismaleimides, trismaleimides or mixtures thereof with maleimide end-caps are used as the dienophile, the resulting polyimides have glass transition temperatures (Tg) as high as 300? C. Polyimide films can be prepared by ultraviolet irradiation of high solids content varnishes of the monomers in a small amount of solvent, e.g., cyclohexanone, dimethyl formamide, N-methylpyrollidone and the like. These novel polyimides are characterized as having high glass transition temperatures, good mechanical properties and improved processing in the manufacture of adhesives, electronic materials and films.

  12. Polyimides by Photochemical Cyclopolymerization

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor)

    2005-01-01

    The novel polyimides of this invention are derived from Diels-Alder cyclopolymerization of photochemically generated bisdienes with dienophiles, such as bismaleimides, trismaleimides and mixtures thereof with maleimide endcaps. Irradiation of one or more diketones produces two distinct hydroxy o-quinodimethane (photoenol) intermediates. These intermediates are trapped via Diels-Alder cycloaddition with appropriate dienophiles, e.g., bismaleimide and/or trismaleimides to give the corresponding polyimides in quantitative yields. When bismaleimides, trismaleimides or mixtures thereof with maleimide end-caps are used as the dienophile, the resulting polyimides have glass transition temperatures (Tg) as high as 300 C. Polyimide films can be prepared by ultraviolet irradiation of high solids content varnishes of the monomers in a small amount of solvent, e.g., cyclohexanone, dimethyl formamide, N-methylpyrollidone and the like. These novel polyimides are characterized as having high glass transition temperatures, good mechanical properties and improved processing in the manufacture of adhesives, electronic materials and films.

  13. Photochemical preparation of CdS hollow microspheres at room temperature and their use in visible-light photocatalysis

    SciTech Connect

    Huang Yuying; Sun Fengqiang; Wu Tianxing; Wu Qingsong; Huang Zhong; Su Heng; Zhang Zihe

    2011-03-15

    CdS hollow microspheres have been successfully prepared by a photochemical preparation technology at room temperature, using polystyrene latex particles as templates, CdSO{sub 4} as cadmium source and Na{sub 2}S{sub 2}O{sub 3} as both sulphur source and photo-initiator. The process involved the deposition of CdS nanoparticles on the surface of polystyrene latex particles under the irradiation of an 8 W UV lamp and the subsequent removal of the latex particles by dispersing in dichloromethane. Photochemical reactions at the sphere/solution interface should be responsible for the formation of hollow spheres. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Such hollow spheres could be used in photocatalysis and showed high photocatalytic activities in photodegradation of methyl blue (MB) in the presence of H{sub 2}O{sub 2}. The method is green, simple, universal and can be extended to prepare other sulphide and oxide hollow spheres. -- Graphical abstract: Taking polystyrene spheres dispersed in a precursor solution as templates, CdS hollow microspheres composed of nanoparticles were successfully prepared via a new photochemical route at room temperature. Display Omitted Research highlights: {yields} Photochemical method was first employed to prepare hollow microspheres. {yields} CdS hollow spheres were first prepared at room temperature using latex spheres. {yields} The polystyrene spheres used as templates were not modified with special groups. {yields}The CdS hollow microspheres showed high visible-light photocatalytic activities.

  14. Photobiologic-mediated fabrication of silver nanoparticles with antibacterial activity.

    PubMed

    Lee, Jeong-Ho; Lim, Jeong-Muk; Velmurugan, Palanivel; Park, Yool-Jin; Park, Youn-Jong; Bang, Keuk-Soo; Oh, Byung-Taek

    2016-09-01

    We present the simple, eco-friendly synthesis of silver nanoparticles (AgNPs) using sunlight or green, red, blue, or white LED light together with Dryopteris crassirhizoma rhizome extract (DCRE) as the reducing and capping agent. The preliminary indication of AgNP production was a color change from yellowish green to brown after light exposure in the presence of DCRE. Optimization of parameters such as pH, inoculum dose, and metal ion concentration played an important role in achieving nanoparticle production in 30min. The spectroscopic and morphological properties of AgNPs were characterized using UV-Vis spectroscopy through the presence of a characteristic surface plasmon resonance (SPR) band for AgNPs, Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). The FT-IR results indicated that the phytochemical present in DCRE was the probable reducing/capping agent involved in the synthesis of AgNPs, and light radiation enhanced nanoparticle production. HR-TEM revealed that the AgNPs were almost spherical with an average size of 5-60nm under all light sources. XRD studies confirmed the face cubic center (fcc) unit cell structure of AgNPs. The synthesized AgNPs showed good antimicrobial activity against Bacillus cereus and Pseudomonas aeruginosa. This study will bring a new insight in ecofriendly production of metal nanoparticles.

  15. Tropospheric Ozone and Photochemical Smog

    NASA Astrophysics Data System (ADS)

    Sillman, S.

    2003-12-01

    The question of air quality in polluted regions represents one of the issues of geochemistry with direct implications for human well-being. Human health and well-being, along with the well-being of plants, animals, and agricultural crops, are dependent on the quality of air we breathe. Since the start of the industrial era, air quality has become a matter of major importance, especially in large cities or urbanized regions with heavy automobile traffic and industrial activity.Concern over air quality existed as far back as the 1600s. Originally, polluted air in cities resulted from the burning of wood or coal, largely as a source of heat. The industrial revolution in England saw a great increase in the use of coal in rapidly growing cities, both for industrial use and domestic heating. London suffered from devastating pollution events during the late 1800s and early 1900s, with thousands of excess deaths attributed to air pollution (Brimblecombe, 1987). With increasing use of coal, other instances also occurred in continental Europe and the USA. These events were caused by directly emitted pollutants (primary pollutants), including sulfur dioxide (SO2), carbon monoxide (CO), and particulates. They were especially acute in cities with northerly locations during fall and winter when sunlight is at a minimum. These original pollution events gave rise to the term "smog" (a combination of smoke and fog). Events of this type have become much less severe since the 1950s in Western Europe and the US, as natural gas replaced coal as the primary source of home heating, industrial smokestacks were designed to emit at higher altitudes (where dispersion is more rapid), and industries were required to install pollution control equipment.Beginning in the 1950s, a new type of pollution, photochemical smog, became a major concern. Photochemical smog consists of ozone (O3) and other closely related species ("secondary pollutants") that are produced photochemically from directly

  16. Understanding the role of gold nanoparticles in enhancing the catalytic activity of manganese oxides in water oxidation reactions.

    PubMed

    Kuo, Chung-Hao; Li, Weikun; Pahalagedara, Lakshitha; El-Sawy, Abdelhamid M; Kriz, David; Genz, Nina; Guild, Curtis; Ressler, Thorsten; Suib, Steven L; He, Jie

    2015-02-16

    The Earth-abundant and inexpensive manganese oxides (MnOx) have emerged as an intriguing type of catalysts for the water oxidation reaction. However, the overall turnover frequencies of MnOx catalysts are still much lower than that of nanostructured IrO2 and RuO2 catalysts. Herein, we demonstrate that doping MnOx polymorphs with gold nanoparticles (AuNPs) can result in a strong enhancement of catalytic activity for the water oxidation reaction. It is observed that, for the first time, the catalytic activity of MnOx/AuNPs catalysts correlates strongly with the initial valence of the Mn centers. By promoting the formation of Mn(3+) species, a small amount of AuNPs (<5%) in α-MnO2/AuNP catalysts significantly improved the catalytic activity up to 8.2 times in the photochemical and 6 times in the electrochemical system, compared with the activity of pure α-MnO2.

  17. Photocatalytic activity of biogenic silver nanoparticles synthesized using yeast ( Saccharomyces cerevisiae) extract

    NASA Astrophysics Data System (ADS)

    Roy, Kaushik; Sarkar, C. K.; Ghosh, C. K.

    2015-11-01

    Synthesis of metallic and semiconductor nanoparticles through physical and chemical route is quiet common but biological synthesis procedures are gaining momentum due to their simplicity, cost-effectivity and eco-friendliness. Here, we report green synthesis of silver nanoparticles from aqueous solution of silver salts using yeast ( Saccharomyces cerevisiae) extract. The nanoparticles formation was gradually investigated by UV-Vis spectrometer. X-ray diffraction analysis was done to identify different phases of biosynthesized Ag nanoparticles. Transmission electron microscopy was performed to study the particle size and morphology of silver nanoparticles. Fourier transform infrared spectroscopy of the nanoparticles was performed to study the role of biomolecules capped on the surface of Ag nanoparticles during interaction. Photocatalytic activity of these biosynthesized nanoparticles was studied using an organic dye, methylene blue under solar irradiation and these nanoparticles showed efficacy in degrading the dye within a few hours of exposure.

  18. Activity of catalytic silver nanoparticles modulated by capping agent hydrophobicity.

    PubMed

    Janani, Seralathan; Stevenson, Priscilla; Veerappan, Anbazhagan

    2014-05-01

    In this paper, a facile in situ method is reported for the preparation of catalytic silver nanoparticles (AgNPs) using N-acyl tyramine (NATA) with variable hydrophobic acyl length. Scanning electron microscopic analysis shows that NATA exists initially as larger aggregates in alkaline aqueous solution. The addition of AgNO3 dissociates these larger aggregate and subsequently promotes the formation of self-assembled NATA and AgNPs. Characterization of AgNPs using UV-vis spectroscopy, scanning electron microscope and transmission electron microscope revealed that the hydrophobic acyl chain length of NATA does not influence the particle size, shape and morphology. All NATA-AgNPs yielded relatively identical values in full width at half-maximum (FWHM) analysis, indicating that the AgNPs prepared with NATA are relatively polydispersed at all tested acyl chain lengths. These nanoparticles are able to efficiently catalyze the reduction of 4-nitro phenol to 4-amino phenol, 2-nitro aniline to 1,2-diamino benzene, 2,4,6-trinitro phenol to 2,4,6-triamino phenol by NaBH4 in an aqueous environment. The reduction reaction rate is determined to be pseudo-first order and the apparent rate constant is linearly dependent on the hydrophobic acyl chain length of the NATA. All reaction kinetics presented an induction period, which is dependent on the N-acyl chain length, indicating that the hydrophobic effects play a critical role in bringing the substrate to the metal nanoparticle surface to induce the catalytic reaction. In this study, however, the five catalytic systems have similar size and polydispersity, differing only in terms of capping agent hydrophobicity, and shows different catalytic activity with respect to the alkyl chain length of the capping agent. As discussed, the ability to modulate the metal nanoparticles catalytic property, by modifying the capping agent hydrophobicity represents a promising future for developing an efficient nanocatalyst without altering the size

  19. Surface plasmon resonance optical sensor and antibacterial activities of biosynthesized silver nanoparticles.

    PubMed

    Bindhu, M R; Umadevi, M

    2014-01-01

    Silver nanoparticles were prepared using aqueous fruit extract of Ananas comosus as reducing agent. These silver nanoparticles showed surface plasmon peak at 439 nm. They were monodispersed and spherical in shape with an average particle size of 10 nm. The crystallinity of these nanoparticles was evident from clear lattice fringes in the HRTEM images and bright circular spots in the SAED pattern. The antibacterial activities of prepared nanoparticles were found to be size-dependent, the smaller nanoparticles showing more bactericidal effect. Aqueous Zn(2+) and Cu(4+) selectivity and sensitivity study of this green synthesized nanoparticle was performed by optical sensor based surface plasmon resonance (SPR) at room temperature.

  20. Surface plasmon resonance optical sensor and antibacterial activities of biosynthesized silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Bindhu, M. R.; Umadevi, M.

    2014-03-01

    Silver nanoparticles were prepared using aqueous fruit extract of Ananas comosus as reducing agent. These silver nanoparticles showed surface plasmon peak at 439 nm. They were monodispersed and spherical in shape with an average particle size of 10 nm. The crystallinity of these nanoparticles was evident from clear lattice fringes in the HRTEM images and bright circular spots in the SAED pattern. The antibacterial activities of prepared nanoparticles were found to be size-dependent, the smaller nanoparticles showing more bactericidal effect. Aqueous Zn2+ and Cu4+ selectivity and sensitivity study of this green synthesized nanoparticle was performed by optical sensor based surface plasmon resonance (SPR) at room temperature.

  1. Plasmonics Resonance Enhanced Active Photothermal Effects of Aluminum and Iron Nanoparticles.

    PubMed

    Chong, Xinyuan; Abboud, Jacques; Zhang, Zhili

    2015-03-01

    Localized Surface Plasmonics Resonance (LSPR) enhanced active photothermal effects of both aluminum nanoparticles (Al NPs) and iron nanoparticles (Fe NPs) are experimentally observed. Photothermally activated motion and ignition by low-energy xenon flash are quantitatively measured. For nanoparticles of comparable sizes, photothermally activated motion height of Fe NPs is about 60% lower than that of Al NPs, while photothermal Minimum Ignition Energy (MIE) of Fe NPs is about 50% lower than that of Al NPs. Joule heating by LSPR enhanced photothermal effects among nanoparticles and subsequently triggered oxidation reactions are found responsible for the motion and ignition of the nanoparticles.

  2. ATP-enhanced peroxidase-like activity of gold nanoparticles.

    PubMed

    Shah, Juhi; Purohit, Rahul; Singh, Ragini; Karakoti, Ajay Singh; Singh, Sanjay

    2015-10-15

    Gold nanoparticles (AuNPs) are known to possess intrinsic biological peroxidase-like activity that has applications in development of numerous biosensors. The reactivity of the Au atoms at the surface of AuNPs is critical to the performance of such biosensors, yet little is known about the effect of biomolecules and ions on the peroxidase-like activity. In this work, the effect of ATP and other biologically relevant molecules and ions over peroxidase-like activity of AuNPs are described. Contrary to the expectation that nanoparticles exposed to biomolecules may lose the catalytic property, ATP and ADP addition enhanced the peroxidase-like activity of AuNPs. The catalytic activity was unaltered by the addition of free phosphate, sulphate and carbonate anions however, addition of ascorbic acid to the reaction mixture diminished the intrinsic peroxidase-like activity of AuNPs, even in the presence of ATP and ADP. In contrast to AuNPs, ATP did not synergize and improve the peroxidase activity of the natural peroxidase enzyme, horseradish peroxidase.

  3. Biosynthesis of selenium nanoparticles by Pantoea agglomerans and their antioxidant activity

    NASA Astrophysics Data System (ADS)

    Torres, S. K.; Campos, V. L.; León, C. G.; Rodríguez-Llamazares, S. M.; Rojas, S. M.; González, M.; Smith, C.; Mondaca, M. A.

    2012-11-01

    The bio-reduction of selenite (Se (IV)) generates nanoparticles with sizes ranging between 30 and 300 nm. Biologic properties of Se nanoparticles, e.g., antioxidant activity, are dependent on the nanoparticle size; smaller particles have greater activity. In this study, the bio-reduction of selenite by Pantoea agglomerans strain UC-32 under aerobic conditions and room temperature to produce bioactive Se nanoparticles smaller than 100 nm was demonstrated. Isolation and purification of the nanoparticles was performed by alkaline lysis. These purified nanoparticles were stabilized with l-cysteine (4 mM). The visualization and characterization of nanoparticles were performed by transmission electron microscopy, energy dispersive X-ray spectroscopy, and scanning electron microscopy. The antioxidant activity of nanoparticles was determined by production of reactive oxygen species using human umbilical vein endothelial cells. Transmission electron microscopy images showed the accumulation of spherical selenium nanoparticles as intracellular and extracellular deposits. The size of Se nanoparticles varied with incubation time. Amorphous Se nanoparticles with size in the order of 100 nm were obtained before 24 h of incubation; but, at 24 h of incubation, the size of the majority of the nanoparticles was in the desirable order of 100 nm and they were not aggregated. Energy dispersive spectroscopy spectra indicated that nanoparticles were composed entirely of selenium. Antioxidant activity of stabilized selenium nanoparticles demonstrated high antioxidant activity when compared to selenite and selenium nanoparticles without stabilization. Stabilized biologically synthetized selenium (0) nanoparticles with size less than 100 nm have a potential application as a food additive with antioxidant properties relevant to human health.

  4. Intrinsic effects of gold nanoparticles on proliferation and invasion activity in SGC-7901 cells.

    PubMed

    Wu, Yucheng; Zhang, Qingqing; Ruan, Zhongbao; Yin, Yigang

    2016-03-01

    Although biomedical applications of functionalized nanoparticles have taken significant strides, biological characterization of unmodified nanoparticles remains unclear. In the present study, we investigated the cell viability and invasion activity of gastric cancer cells after treatment with gold nanoparticles. The growth of SGC-7901 cells was inhibited significantly after treatment with 5-nm gold nanoparticles, and the cell invasion decreased markedly. These effects were not seen by different size gold nanoparticles (10, 20 and 40 nm). The attenuated invasion activity may be associated with the decreased expression of matrix metalloproteinase 9 and intercellular adhesion molecule-1. These data indicated that the response of SGC-7901 cells to gold nanoparticles was strongly associated with their unique size-dependent physiochemical properties. Therefore, we provided new evidence for the effect of gold nanoparticles on gastric cancer cell proliferation and invasion in vitro, making a contribution to the application of gold nanoparticles to novel therapies in gastric cancer.

  5. Enhanced antibacterial activity of silver/polyrhodanine-composite-decorated silica nanoparticles.

    PubMed

    Song, Jooyoung; Kim, Hyunyoung; Jang, Yoonsun; Jang, Jyongsik

    2013-11-27

    This work describes the synthesis of silver/polyrhodanine-composite-decorated silica nanoparticles and their antibacterial activity. Polymerization of polyrhodanine proceeded preferentially on the surface of the silica nanoparticles where Ag(+) ions were located. In addition, the embedded Ag(+) ions were reduced to form metallic Ag nanoparticles; consequently, silver/polyrhodanine-composite nanoparticles (approximately 7 nm in diameter) were formed on the surface of the silica nanoparticles. The resulting nanostructure was investigated using electron microscopy, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy. The silver/polyrhodanine-nanocomposite-decorated silica nanoparticles exhibited excellent antimicrobial activity toward gram-negative Escherichia coli and gram-positive Staphylococcus aureus because of the antibacterial effects of the silver nanoparticles and the polyrhodanine. The silver/polyrhodanine-composite nanoparticles may therefore have potential for use as a long-term antibacterial agent.

  6. Antimicrobial and mosquitocidal activity of microbial synthesized silver nanoparticles.

    PubMed

    Soni, Namita; Prakash, Soam

    2015-03-01

    Microbial synthesis of nanoparticles is a green approach that interconnects nanotechnology and microbial biotechnology. Here, we synthesized the silver nanoparticles (AgNPs) using bacterial strains of Listeria monocytogenes, Bacillus subtilius and Streptomyces anulatus. We tested the efficacy of AgNPs against the larvae, pupae and adults of Anopheles stephensi and Culex quinquefasciatus. We have also investigated the antifungal activity of AgNPs against the soil keratinophilic fungus of Chrysosporium keratinophilum. The efficacy tests were then performed at different concentrations and varying numbers of hours by probit analysis. The results were obtained using a UV-visible spectrophotometer, and the images were recorded with a transmission electron microscope (TEM). The synthesized AgNPs were in varied shape and sizes. The larvae and pupae of Cx. quinquefasciatus were found highly susceptible to AgNPs synthesized using the L. monocytogenes, B. subtilius and S. anulatus than the An. stephensi, while the adults of An. stephensi were found more susceptible to the AgNPs synthesized using the L. monocytogenes, B. subtilius and S. anulatus the Cx. quinquefasciatus. Further, these nanoparticles have also been tested as antifungal activity against the entomopathogenic fungus C. keratinophilum. The higher zone of inhibition occurred at the concentration level of 50 μl. This study gives an innovative approach to develop eco-friendly AgNPs which act as an effective antifungal agent/fungicide and insecticide.

  7. Enhanced silver nanoparticle synthesis by optimization of nitrate reductase activity.

    PubMed

    Vaidyanathan, Ramanathan; Gopalram, Shubaash; Kalishwaralal, Kalimuthu; Deepak, Venkataraman; Pandian, Sureshbabu Ram Kumar; Gurunathan, Sangiliyandi

    2010-01-01

    Nanostructure materials are attracting a great deal of attention because of their potential for achieving specific processes and selectivity, especially in biological and pharmaceutical applications. The generation of silver nanoparticles using optimized nitrate reductase for the reduction of Ag(+) with the retention of enzymatic activity in the complex is being reported. This report involves the optimization of enzyme activity to bring about enhanced nanoparticle synthesis. Response surface methodology and central composite rotary design (CCRD) were employed to optimize a fermentation medium for the production of nitrate reductase by Bacillus licheniformis at pH 8. The four variables involved in the study of nitrate reductase were Glucose, Peptone, Yeast extract and KNO(3). Glucose had a significant effect on nitrate reductase production. The optimized medium containing (%) Glucose: 1.5, Peptone: 1, Yeast extract: 0.35 and KNO(3): 0.35 resulted in a nitrate reductase activity of 452.206 U/ml which is same as that of the central level. The medium A (showing least nitrate reductase activity) and the medium B (showing maximum nitrate reductase activity) were compared for the synthesis. Spectrophotometric analysis revealed that the particles exhibited a peak at 431 nm and the A(431) for the medium B was 2-fold greater than that of the medium A. The particles were also characterized using TEM. The particles synthesized using the optimized enzyme activity ranged from 10 to 80 nm and therefore can be extended to various medicinal applications.

  8. Polyesters by Photochemical Cyclopolymerization

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor)

    2002-01-01

    The polyesters of this invention are derived from a Diels-Alder cyclopolymerization of a photochemically generated bisdiene with dienophiles, such as di(acrylates), tri (acrylates), di(methacrylates), tri(methacrylates) and mixtures thereof with mono(methacrylates) or mono(acrylate) end-caps. Irradiation of one or more diketones produces two distinct hydroxy o-quinodimethane (photoenol) intermediates. These intermediates are trapped via a Diels-Alder cycloaddition with appropriate dienophiles, e.g., di(acrylates) to give the corresponding in polyesters quantitative yields. When di(acrylates), tri(acrylates) and di and tri(methacrylates) or mixtures thereof with monoacrylate end-caps are used as the dienophile, the resulting polyesters have glass transition temperatures (Tg) as high as 200 C. Polyesters films can be prepared by ultraviolet irradiation of high solids content varnishes of the monomers in a small amount of solvent, e.g., cyclohexanone, dimethyl formamide, N-methylpyrollidone and the like. These polyesters, i.e. polyesters are characterized as having high glass transition temperatures, good mechanical properties and improved processing in the manufacture of composites, adhesives, electronic materials and films.

  9. Polyimides by Photochemical Cyclopolymerization

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor)

    2003-01-01

    The polyimides of this invention are derived from a Diels-Alder cyclopolymerization of a photochemically generated bisdiene with dienophiles, such as bismaleimides, trismaleimides and mixtures thereof with maleimide end-caps. Irradiation of one or more diketones produces two distinct hydroxy o-quinodimethane (photoenol) intermediates. These intermediates are trapped via a Diels-Alder cycloaddition with appropriate dienophiles, e.g., bismaleimide and/or trismaleimides to give the corresponding polyimides in quantitative yields. When bismaleimides, trismaleimides or mixtures thereof with maleimide end-caps are used as the dienophile, the resulting polyimides have glass transition temperatures (Tg) as high as 300 C. Polyimide films can be prepared by ultraviolet irradiation of high solids content varnishes of the monomers in a small amount of solvent, e.g., cyclohexanone, dimethyl formamide, N-methylpyrollidone and the like. These polyimides are characterized as having high glass transition temperatures, good mechanical properties and improved processing in the manufacture of adhesives, electronic materials and films.

  10. Synthesis of ZnO nanoparticles and evaluation of antioxidant and cytotoxic activity.

    PubMed

    Das, Dhaneswar; Nath, Bikash Chandra; Phukon, Pinkee; Kalita, Amarjyoti; Dolui, Swapan Kumar

    2013-11-01

    ZnO nanoparticles were synthesized by thermal decomposition method and were characterized by UV-vis spectroscopy, XRD, SEM, EDX and TEM analysis. The resultant nanoparticles are nearly spherical and size is in the range of 40-50 nm. The antioxidant behavior of ZnO nanoparticles was assessed by scavenging free radicals of 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) with varying nanoparticle concentration and time interval individually. The DPPH scavenging activity was monitored by UV-vis spectrophotometer. ZnO nanoparticles were also showing cytotoxic activity which was studied by hemolytic potentiality test.

  11. Influence of Magnetite Nanoparticles on Human Leukocyte Activity

    NASA Astrophysics Data System (ADS)

    Džarová, Anežka; Dubničková, Martina; Závišová, Vlasta; Koneracká, Martina; Kopčanský, Peter; Gojzewski, Hubert; Timko, Milan

    2010-12-01

    Chemically synthesized magnetite particles coated by sodium oleate and PEG (MNP), and magnetosomes (MS) influence the process of phagocytosis and the metabolic activity (lysozyme and peroxidase activity) in leukocytes. Lysozyme activity is oxygen-independent liquidation mechanisms of engulfed microorganism, peroxidase activity is an oxygen-dependent mechanism. Both tested types of nanoparticles lysed leukocyte cells during incubation. MNP at concentrations of 10 and 20 μg/mL lysed almost all leukocytes and their cell viability was in the 14±0.05% range. On the other hand MS begin to influence leukocytes activity at the concentration of 1 μg/ml and this influence grows with increasing concentration up to 20 μg/ml. MS are more suitable for biological applications than MNP which are more aggressive material than MS. MS should not be used above 10 μg/mL.

  12. SERS-active nanoparticle aggregate technology for tags and seals

    SciTech Connect

    Brown, Leif O; Montoya, Velma M; Havrilla, George J; Doorn, Stephen K

    2010-06-03

    In this paper, we describe our efforts to create a modern tagging and sealing technology for international safeguards application. Our passive tagging methods are based on SANAs (SERS-Active Nanoparticle Aggregates; SERS: Surface Enhanced Raman Scattering). These SANAs offer robust spectral barcoding capability in an inexpensive tag/seal, with the possibility of rapid in-field verification that requires no human input. At INMM 2009, we introduced SANAs, and showed approaches to integrating our technology with tags under development at Sandia National Laboratories (SNL). Here, we will focus on recent LANL development work, as well as adding additional dimensionality to the barcoding technique. The field of international safeguards employs a broad array of tags, seals, and tamper-indicating devices to assist with identification, tracking, and verification of components and materials. These devices each have unique strengths suited to specific applications, and span a range of technologies from passive metal cup seals and adhesive seals to active, remotely monitored fiber optic seals. Regardless of the technology employed, essential characteristics center around security, environmental and temporal stability, ease of use, and the ability to provide confidence to all parties. Here, we present a new inexpensive tagging technology that will deliver these attributes, while forming the basis of either a new seal, or as a secure layer added to many existing devices. Our approach uses the Surface Enhanced Raman Scattering (SERS) response from SANAs (SERS-Active Nanoparticle Aggregates, Figure 1) to provide a unique identifier or signature for tagging applications. SANAs are formed from gold or silver nanoparticles in the 40-80 nm size range. A chemical dye is installed on the nanoparticle surface, and the nanoparticles are then aggregated into ensembles of {approx}100 to 500 nm diameter, prior to being coated with silica. The silica shell protects the finished SANA from

  13. Method of making gold thiolate and photochemically functionalized microcantilevers

    DOEpatents

    Boiadjiev, Vassil I [Knoxville, TN; Brown, Gilbert M [Knoxville, TN; Pinnaduwage, Lal A [Knoxville, TN; Thundat, Thomas G [Knoxville, TN; Bonnesen, Peter V [Knoxville, TN; Goretzki, Gudrun [Nottingham, GB

    2009-08-25

    Highly sensitive sensor platforms for the detection of specific reagents, such as chromate, gasoline and biological species, using microcantilevers and other microelectromechanical systems (MEMS) whose surfaces have been modified with photochemically attached organic monolayers, such as self-assembled monolayers (SAM), or gold-thiol surface linkage are taught. The microcantilever sensors use photochemical hydrosilylation to modify silicon surfaces and gold-thiol chemistry to modify metallic surfaces thereby enabling individual microcantilevers in multicantilever array chips to be modified separately. Terminal vinyl substituted hydrocarbons with a variety of molecular recognition sites can be attached to the surface of silicon via the photochemical hydrosilylation process. By focusing the activating UV light sequentially on selected silicon or silicon nitride hydrogen terminated surfaces and soaking or spotting selected metallic surfaces with organic thiols, sulfides, or disulfides, the microcantilevers are functionalized. The device and photochemical method are intended to be integrated into systems for detecting specific agents including chromate groundwater contamination, gasoline, and biological species.

  14. Photochemical Phenomenology Model for the New Millennium

    NASA Technical Reports Server (NTRS)

    Bishop, James; Evans, J. Scott

    2001-01-01

    The "Photochemical Phenomenology Model for the New Millennium" project tackles the issue of reengineering and extension of validated physics-based modeling capabilities ("legacy" computer codes) to application-oriented software for use in science and science-support activities. While the design and architecture layouts are in terms of general particle distributions involved in scattering, impact, and reactive interactions, initial Photochemical Phenomenology Modeling Tool (PPMT) implementations are aimed at construction and evaluation of photochemical transport models with rapid execution for use in remote sensing data analysis activities in distributed systems. Current focus is on the Composite Infrared Spectrometer (CIRS) data acquired during the CASSINI flyby of Jupiter. Overall, the project has stayed on the development track outlined in the Year 1 annual report and most Year 2 goals have been met. The issues that have required the most attention are: implementation of the core photochemistry algorithms; implementation of a functional Java Graphical User Interface; completion of a functional CORBA Component Model framework; and assessment of performance issues. Specific accomplishments and the difficulties encountered are summarized in this report. Work to be carried out in the next year center on: completion of testing of the initial operational implementation; its application to analysis of the CASSINI/CIRS Jovian flyby data; extension of the PPMT to incorporate additional phenomenology algorithms; and delivery of a mature operational implementation.

  15. Alumoxane/ferroxane nanoparticles for the removal of viral pathogens: the importance of surface functionality to nanoparticle activity.

    PubMed

    Maguire-Boyle, Samuel J; Liga, Michael V; Li, Qilin; Barron, Andrew R

    2012-09-21

    A bi-functional nano-composite coating has been created on a porous Nomex® fabric support as a trap for aspirated virus contaminated water. Nomex® fabric was successively dip-coated in solutions containing cysteic acid functionalized alumina (alumoxane) nanoparticles and cysteic acid functionalized iron oxide (ferroxane) nanoparticles to form a nanoparticle coated Nomex® (NPN) fabric. From SEM and EDX the nanoparticle coating of the Nomex® fibers is uniform, continuous, and conformal. The NPN was used as a filter for aspirated bacteriophage MS2 viruses using end-on filtration. All measurements were repeated to give statistical reliability. The NPN fabrics show a large decrease as compared to Nomex® alone or alumoxane coated Nomex®. An increase in the ferroxane content results in an equivalent increase in virus retention. This suggests that it is the ferroxane that has an active role in deactivating and/or binding the virus. Heating the NPN to 160 °C results in the loss of cysteic acid functional groups (without loss of the iron nanoparticle's core structure) and the resulting fabric behaves similar to that of untreated Nomex®, showing that the surface functionalization of the nanoparticles is vital for the surface collapse of aspirated water droplets and the absorption and immobilization of the MS2 viruses. Thus, for virus immobilization, it is not sufficient to have iron oxide nanoparticles per se, but the surface functionality of a nanoparticle is vitally important in ensuring efficacy.

  16. Nanoparticle cluster gas sensor: Pt activated SnO2 nanoparticles for NH3 detection with ultrahigh sensitivity.

    PubMed

    Liu, Xu; Chen, Nan; Han, Bingqian; Xiao, Xuechun; Chen, Gang; Djerdj, Igor; Wang, Yude

    2015-09-28

    Pt activated SnO2 nanoparticle clusters were synthesized by a simple solvothermal method. The structure, morphology, chemical state and specific surface area were analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption studies, respectively. The SnO2 nanoparticle cluster matrix consists of tens of thousands of SnO2 nanoparticles with an ultra-small grain size estimated to be 3.0 nm. And there are abundant random-packed wormhole-like pores, caused by the inter-connection of the SnO2 nanoparticles, throughout each cluster. The platinum element is present in two forms including metal (Pt) and tetravalent metal oxide (PtO2) in the Pt activated SnO2 nanoparticle clusters. The as-synthesized pure and Pt activated SnO2 nanoparticle clusters were used to fabricate gas sensor devices. It was found that the gas response toward 500 ppm of ammonia was improved from 6.48 to 203.44 through the activation by Pt. And the results indicate that the sensor based on Pt activated SnO2 not only has ultrahigh sensitivity but also possesses good response-recovery properties, linear dependence, repeatability, selectivity and long-term stability, demonstrating the potential to use Pt activated SnO2 nanoparticle clusters as ammonia gas sensors. At the same time, the formation mechanisms of the unique nanoparticle clusters and highly enhanced sensitivity are also discussed.

  17. Hairlike Percutaneous Photochemical Sensors

    NASA Technical Reports Server (NTRS)

    George, Thomas; Loeb, Gerald

    2004-01-01

    Instrumentation systems based on hairlike fiber-optic photochemical sensors have been proposed as minimally invasive means of detecting biochemicals associated with cancer and other diseases. The fiber-optic sensors could be mass-produced as inexpensive, disposable components. The sensory tip of a fiber-optic sensor would be injected through the patient's skin into subcutaneous tissue. A biosensing material on the sensory tip would bind or otherwise react with the biochemical(s) of interest [the analyte(s)] to produce a change in optical properties that would be measured by use of an external photonic analyzer. After use, a fiber-optic sensor could be simply removed by plucking it out with tweezers. A fiber-optic sensor according to the proposal would be of the approximate size and shape of a human hair, and its sensory tip would resemble a follicle. Once inserted into a patient's subcutaneous tissue, the sensor would even more closely resemble a hair growing from a follicle (see Figure 1). The biosensing material on the sensory tip could consist of a chemical and/or cells cultured and modified for the purpose. The biosensing material would be contained within a membrane that would cover the tip. If the membrane were not permeable by an analyte, then it would be necessary to create pores in the membrane that would be large enough to allow analyte molecules to diffuse to the biosensing material, but not so large as to allow cells (if present as part of the biosensing material) to diffuse out. The end of the fiber-optic sensor opposite the sensory tip would be inserted in a fiberoptic socket in the photonic analyzer.

  18. Eugenol-loaded chitosan nanoparticles: II. Application in bio-based plastics for active packaging.

    PubMed

    Woranuch, Sarekha; Yoksan, Rangrong

    2013-07-25

    The aim of the present research was to study the possibility of using eugenol-loaded chitosan nanoparticles as antioxidants for active bio-based packaging material. Eugenol-loaded chitosan nanoparticles were incorporated into thermoplastic flour (TPF) - a model bio-based plastic - through an extrusion process at temperatures above 150°C. The influences of eugenol-loaded chitosan nanoparticles on crystallinity, morphology, thermal properties, radical scavenging activity, reducing power, tensile properties and barrier properties of TPF were investigated. Although the incorporation of 3% (w/w) of eugenol-loaded chitosan nanoparticles significantly reduced the extensibility and the oxygen barrier property of TPF, it provided antioxidant activity and improved the water vapor barrier property. In addition, TPF containing eugenol-loaded chitosan nanoparticles exhibited superior radical scavenging activity and stronger reducing power compared with TPF containing naked eugenol. The results suggest the applicability of TPF containing eugenol-loaded chitosan nanoparticles as an antioxidant active packaging material.

  19. Antimicrobial activity of iron oxide nanoparticle upon modulation of nanoparticle-bacteria interface

    PubMed Central

    Arakha, Manoranjan; Pal, Sweta; Samantarrai, Devyani; Panigrahi, Tapan K.; Mallick, Bairagi C.; Pramanik, Krishna; Mallick, Bibekanand; Jha, Suman

    2015-01-01

    Investigating the interaction patterns at nano-bio interface is a key challenge for safe use of nanoparticles (NPs) to any biological system. The study intends to explore the role of interaction pattern at the iron oxide nanoparticle (IONP)-bacteria interface affecting antimicrobial propensity of IONP. To this end, IONP with magnetite like atomic arrangement and negative surface potential (n-IONP) was synthesized by co-precipitation method. Positively charged chitosan molecule coating was used to reverse the surface potential of n-IONP, i.e. positive surface potential IONP (p-IONP). The comparative data from fourier transform infrared spectroscope, XRD, and zeta potential analyzer indicated the successful coating of IONP surface with chitosan molecule. Additionally, the nanocrystals obtained were found to have spherical size with 10–20 nm diameter. The BacLight fluorescence assay, bacterial growth kinetic and colony forming unit studies indicated that n-IONP (<50 μM) has insignificant antimicrobial activity against Bacillus subtilis and Escherichia coli. However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP. Additionally, the assay to study reactive oxygen species (ROS) indicated relatively higher ROS production upon p-IONP treatment of the bacteria. The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity. PMID:26437582

  20. Antimicrobial activity of iron oxide nanoparticle upon modulation of nanoparticle-bacteria interface

    NASA Astrophysics Data System (ADS)

    Arakha, Manoranjan; Pal, Sweta; Samantarrai, Devyani; Panigrahi, Tapan K.; Mallick, Bairagi C.; Pramanik, Krishna; Mallick, Bibekanand; Jha, Suman

    2015-10-01

    Investigating the interaction patterns at nano-bio interface is a key challenge for safe use of nanoparticles (NPs) to any biological system. The study intends to explore the role of interaction pattern at the iron oxide nanoparticle (IONP)-bacteria interface affecting antimicrobial propensity of IONP. To this end, IONP with magnetite like atomic arrangement and negative surface potential (n-IONP) was synthesized by co-precipitation method. Positively charged chitosan molecule coating was used to reverse the surface potential of n-IONP, i.e. positive surface potential IONP (p-IONP). The comparative data from fourier transform infrared spectroscope, XRD, and zeta potential analyzer indicated the successful coating of IONP surface with chitosan molecule. Additionally, the nanocrystals obtained were found to have spherical size with 10-20 nm diameter. The BacLight fluorescence assay, bacterial growth kinetic and colony forming unit studies indicated that n-IONP (<50 μM) has insignificant antimicrobial activity against Bacillus subtilis and Escherichia coli. However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP. Additionally, the assay to study reactive oxygen species (ROS) indicated relatively higher ROS production upon p-IONP treatment of the bacteria. The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity.

  1. Thermal activation in statistical clusters of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Hovorka, O.

    2017-02-01

    This article presents a kinetic Monte-Carlo study of thermally activated magnetisation dynamics in clusters of statistically distributed magnetic nanoparticles. The structure of clusters is assumed to be of fractal nature, consistently with recent observations of magnetic particle aggregation in cellular environments. The computed magnetisation relaxation decay and frequency-dependent hysteresis loops are seen to significantly depend on the fractal dimension of aggregates, leading to accelerated magnetisation relaxation and reduction in the size of hysteresis loops as the fractal dimension increases from one-dimensional-like to three-dimensional-like clusters. Discussed are implications for applications in nanomedicine, such as magnetic hyperthermia or magnetic particle imaging.

  2. Esterase activity of BSA-ZnO nanoparticle complex

    NASA Astrophysics Data System (ADS)

    Bhogale, A.; Nair, A.; Patel, N.; Miotello, A.; Kothari, D. C.

    2014-04-01

    The effect of Zinc Oxide Nanoparticles (ZnO NPs) on functional properties of Bovine Serum Albumin (BSA) protein was studied. ZnO NPs were synthesized with average size of ˜7.5 nm as obtained from TEM analysis. The catalytic conversion of p-nitrophenylacetate (PNPA) to p-nitrophenol in the presence of BSA attached with ZnO NPs was examined by UV-Vis spectroscopy at room temperature. The result suggests that esterase activity of BSA is significantly enhanced (6 times) due to the ground state BSA-ZnO complex formation.

  3. Stability and phase transfer of catalytically active platinum nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    Sriram, Indira; Curtin, Alexandra E.; Chiaramonti, Ann N.; Cuchiaro, J. Hunter; Weidner, Andrew R.; Tingley, Tegan M.; Greenlee, Lauren F.; Jeerage, Kavita M.

    2015-05-01

    In this work, we present a robust synthesis protocol for platinum nanoparticles that yields a monomodal dispersion of particles that are approximately 100 nm in diameter. We determine that these particles are actually agglomerates of much smaller particles, creating a "raspberry" morphology. We demonstrate that these agglomerates are stable at room temperature for at least 8 weeks by dynamic light scattering. Furthermore, we demonstrate consistent electrocatalytic activity for methanol oxidation. Finally, we quantitatively explore the relationship between dispersion solvent and particle agglomeration; specifically, particles are found to agglomerate abruptly as solvent polarity decreases.

  4. Antibacterial activity of pH-dependent biosynthesized silver nanoparticles against clinical pathogen.

    PubMed

    Chitra, Kethirabalan; Annadurai, Gurusamy

    2014-01-01

    Simple, nontoxic, environmental friendly method is employed for the production of silver nanoparticles. In this study the synthesized nanoparticles UV absorption band occurred at 400 nm because of the surface Plasmon resonance of silver nanoparticles. The pH of the medium plays important role in the synthesis of control shaped and sized nanoparticles. The colour intensity of the aqueous solution varied with pH. In this study, at pH 9, the colour of the aqueous solution was dark brown, whereas in pH 5 the colour was yellowish brown; the colour difference in the aqueous solution occurred due to the higher production of silver nanoparticles. The antibacterial activity of biosynthesized silver nanoparticles was carried out against E. coli. The silver nanoparticles synthesized at pH 9 showed maximum antibacterial activity at 50 μL.

  5. Synergistic bactericidal activity of Ag-TiO₂ nanoparticles in both light and dark conditions.

    PubMed

    Li, Minghua; Noriega-Trevino, Maria Eugenia; Nino-Martinez, Nereyda; Marambio-Jones, Catalina; Wang, Jinwen; Damoiseaux, Robert; Ruiz, Facundo; Hoek, Eric M V

    2011-10-15

    High-throughput screening was employed to evaluate bactericidal activities of hybrid Ag-TiO₂ nanoparticles comprising variations in TiO₂ crystalline phase, Ag content, and synthesis method. Hybrid Ag-TiO₂ nanoparticles were prepared by either wet-impregnation or UV photo deposition onto both Degussa P25 and DuPont R902 TiO₂ nanoparticles. The presence of Ag was confirmed by ICP, TEM, and XRD analysis. The size of Ag nanoparticles formed on anatase/rutile P25 TiO₂ nanoparticles was smaller than those formed on pure rutile R902. When activated by UV light, all hybrid Ag-TiO₂ nanoparticles exhibited stronger bactericidal activity than UV alone, Ag/UV, or UV/TiO₂. For experiments conducted in the dark, bactericidal activity of Ag-TiO₂ nanoparticles was greater than either bare TiO₂ (inert) or pure Ag nanoparticles, suggesting that the hybrid materials produced a synergistic antibacterial effect unrelated to photoactivity. Moreover, less Ag(+) dissolved from Ag-TiO₂ nanoparticles than from Ag nanoparticles, indicating the antibacterial activities of Ag-TiO₂ was not only caused by releasing of toxic metal ions. It is clear that nanotechnology can produce more effective bactericides; however, the challenge remains to identify practical ways to take advantage of these exciting new material properties.

  6. Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

    SciTech Connect

    Laha, Dipranjan; Pramanik, Arindam; Laskar, Aparna; Jana, Madhurya; Pramanik, Panchanan; Karmakar, Parimal

    2014-11-15

    Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain.

  7. Activation of latent HIV using drug-loaded nanoparticles.

    PubMed

    Kovochich, Michael; Marsden, Matthew D; Zack, Jerome A

    2011-04-05

    Antiretroviral therapy is currently only capable of controlling HIV replication rather than completely eradicating virus from patients. This is due in part to the establishment of a latent virus reservoir in resting CD4+ T cells, which persists even in the presence of HAART. It is thought that forced activation of latently infected cells could induce virus production, allowing targeting of the cell by the immune response. A variety of molecules are able to stimulate HIV from latency. However no tested purging strategy has proven capable of eliminating the infection completely or preventing viral rebound if therapy is stopped. Hence novel latency activation approaches are required. Nanoparticles can offer several advantages over more traditional drug delivery methods, including improved drug solubility, stability, and the ability to simultaneously target multiple different molecules to particular cell or tissue types. Here we describe the development of a novel lipid nanoparticle with the protein kinase C activator bryostatin-2 incorporated (LNP-Bry). These particles can target and activate primary human CD4+ T-cells and stimulate latent virus production from human T-cell lines in vitro and from latently infected cells in a humanized mouse model ex vivo. This activation was synergistically enhanced by the HDAC inhibitor sodium butyrate. Furthermore, LNP-Bry can also be loaded with the protease inhibitor nelfinavir (LNP-Bry-Nel), producing a particle capable of both activating latent virus and inhibiting viral spread. Taken together these data demonstrate the ability of nanotechnological approaches to provide improved methods for activating latent HIV and provide key proof-of-principle experiments showing how novel delivery systems may enhance future HIV therapy.

  8. Manganese nanoparticle activates mitochondrial dependent apoptotic signaling and autophagy in dopaminergic neuronal cells

    SciTech Connect

    Afeseh Ngwa, Hilary; Kanthasamy, Arthi; Gu, Yan; Fang, Ning; Anantharam, Vellareddy; Kanthasamy, Anumantha G.

    2011-11-15

    The production of man-made nanoparticles for various modern applications has increased exponentially in recent years, but the potential health effects of most nanoparticles are not well characterized. Unfortunately, in vitro nanoparticle toxicity studies are extremely limited by yet unresolved problems relating to dosimetry. In the present study, we systematically characterized manganese (Mn) nanoparticle sizes and examined the nanoparticle-induced oxidative signaling in dopaminergic neuronal cells. Differential interference contrast (DIC) microscopy and transmission electron microscopy (TEM) studies revealed that Mn nanoparticles range in size from single nanoparticles ({approx} 25 nM) to larger agglomerates when in treatment media. Manganese nanoparticles were effectively internalized in N27 dopaminergic neuronal cells, and they induced a time-dependent upregulation of the transporter protein transferrin. Exposure to 25-400 {mu}g/mL Mn nanoparticles induced cell death in a time- and dose-dependent manner. Mn nanoparticles also significantly increased ROS, accompanied by a caspase-mediated proteolytic cleavage of proapoptotic protein kinase C{delta} (PKC{delta}), as well as activation loop phosphorylation. Blocking Mn nanoparticle-induced ROS failed to protect against the neurotoxic effects, suggesting the involvement of other pathways. Further mechanistic studies revealed changes in Beclin 1 and LC3, indicating that Mn nanoparticles induce autophagy. Primary mesencephalic neuron exposure to Mn nanoparticles induced loss of TH positive dopaminergic neurons and neuronal processes. Collectively, our results suggest that Mn nanoparticles effectively enter dopaminergic neuronal cells and exert neurotoxic effects by activating an apoptotic signaling pathway and autophagy, emphasizing the need for assessing possible health risks associated with an increased use of Mn nanoparticles in modern applications. -- Highlights: Black-Right-Pointing-Pointer Mn nanoparticles

  9. Modeling the heterogeneous catalytic activity of a single nanoparticle using a first passage time distribution formalism

    NASA Astrophysics Data System (ADS)

    Das, Anusheela; Chaudhury, Srabanti

    2015-11-01

    Metal nanoparticles are heterogeneous catalysts and have a multitude of non-equivalent, catalytic sites on the nanoparticle surface. The product dissociation step in such reaction schemes can follow multiple pathways. Proposed here for the first time is a completely analytical theoretical framework, based on the first passage time distribution, that incorporates the effect of heterogeneity in nanoparticle catalysis explicitly by considering multiple, non-equivalent catalytic sites on the nanoparticle surface. Our results show that in nanoparticle catalysis, the effect of dynamic disorder is manifested even at limiting substrate concentrations in contrast to an enzyme that has only one well-defined active site.

  10. Gold nanoparticles-graphene hybrids as active catalysts for Suzuki reaction

    SciTech Connect

    Li, Yang; Fan, Xiaobin; Qi, Junjie; Ji, Junyi; Wang, Shulan; Zhang, Guoliang; Zhang, Fengbao

    2010-10-15

    Graphene was successfully modified with gold nanoparticles in a facile route by reducing chloroauric acid in the presence of sodium dodecyl sulfate, which is used as both a surfactant and reducing agent. The gold nanoparticles-graphene hybrids were characterized by high-resolution transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction and energy X-ray spectroscopy. We demonstrate for the first time that the gold nanoparticles-graphene hybrids can act as efficient catalysts for the Suzuki reaction in water under aerobic conditions. The catalytic activity of gold nanoparticles-graphene hybrids was influenced by the size of the gold nanoparticles.

  11. Hydrothermal Synthesis of Ultrasmall Pt Nanoparticles as Highly Active Electrocatalysts for Methanol Oxidation

    PubMed Central

    Ji, Wenhai; Qi, Weihong; Tang, Shasha; Peng, Hongcheng; Li, Siqi

    2015-01-01

    Ultrasmall nanoparticles, with sizes in the 1–3 nm range, exhibit unique properties distinct from those of free molecules and larger-sized nanoparticles. Demonstrating that the hydrothermal method can serve as a facile method for the synthesis of platinum nanoparticles, we successfully synthesized ultrasmall Pt nanoparticles with an average size of 2.45 nm, with the aid of poly(vinyl pyrrolidone) (PVP) as reducing agents and capping agents. Because of the size effect, these ultrasmall Pt nanoparticles exhibit a high activity toward the methanol oxidation reaction.

  12. Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles

    PubMed Central

    Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Chifiriuc, Mariana Carmen; Costescu, Adrian; Le Coustumer, Philippe; Predoi, Daniela

    2013-01-01

    The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. The aim of this study was the evaluation of Ca10−xAgx(PO4)6(OH)2 nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures. PMID:23509801

  13. Research opportunities in photochemical sciences

    SciTech Connect

    1996-07-01

    The workshop entitled {open_quotes}Research Opportunities in Photochemical Sciences{close_quotes} was initiated by the U.S. Department of Energy (DOE), Office of Energy Research (ER), Office of Basic Energy Sciences (BES), Division of Chemical Sciences. The National Renewable Energy Laboratory (NREL) in Golden, Colorado was requested by ER to host the workshop. It was held February 5-8, 1996 at the Estes Park Conference Center, Estes Park, CO, and attended by about 115 leading scientists and engineers from the U.S., Japan, and Europe; program managers for the DOE ER and Energy Efficiency and Renewable Energy (EERE) programs also attended. The purpose of the workshop was to bridge the communication gap between the practioneers and supporters of basic research in photochemical science and the practioneers and supporters of applied research and development in technologies related to photochemical science. For the purposes of the workshop the definition of the term {open_quotes}photochemical science{close_quotes} was broadened to include homogeneous photochemistry, heterogeneous photochemistry, photoelectrochemistry, photocatalysis, photobiology (for example, the light-driven processes of biological photosynthesis and proton pumping), artificial photosynthesis, solid state photochemistry, and solar photochemistry. The technologies under development through DOE support that are most closely related to photochemical science, as defined above, are the renewable energy technologies of photovoltaics, biofuels, hydrogen energy, carbon dioxide reduction and utilization, and photocatalysis for environmental cleanup of water and air. Individual papers were processed separately for the United states Department of Energy databases.

  14. Anticancer and enhanced antimicrobial activity of biosynthesizd silver nanoparticles against clinical pathogens

    NASA Astrophysics Data System (ADS)

    Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Vanaja, Mahendran; Annadurai, Gurusamy

    2016-07-01

    The present investigation shows the biosynthesis of eco-friendly silver nanoparticles using culture supernatant of Enterococcus sp. and study the effect of enhanced antimicrobial activity, anticancer activity against pathogenic bacteria, fungi and cancer cell lines. Silver nanoparticles was synthesized by adding 1 mM silver nitrate into the 100 ml of 24 h freshly prepared culture supernatant of Enterococcus sp. and were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Selected Area Diffraction X-Ray (SAED), Energy Dispersive X Ray (EDX) and Fourier Transform Infra red Spectroscopy (FT-IR). The synthesized silver nanoparticles were impregnated with commercial antibiotics for evaluation of enhanced antimicrobial activity. Further these synthesized silver nanoparticles were assessed for its anticancer activity against cancer cell lines. In this study crystalline structured nanoparticles with spherical in the size ranges from 10 to 80 nm and it shows excellent enhanced antimicrobial activity than the commercial antibiotics. The in vitro assay of silver nanoparticles on anticancer have great potential to inhibit the cell viability. Amide linkages and carboxylate groups of proteins from Enterococcus sp. may bind with silver ions and convert into nanoparticles. The activities of commercial antibiotics were enhanced by coating silver nanoparticles shows significant improved antimicrobial activity. Silver nanoparticles have the great potential to inhibit the cell viability of liver cancer cells lines (HepG2) and lung cancer cell lines (A549).

  15. Preparation, characterization and in vitro antiviral activity evaluation of foscarnet-chitosan nanoparticles.

    PubMed

    Russo, E; Gaglianone, N; Baldassari, S; Parodi, B; Cafaggi, S; Zibana, C; Donalisio, M; Cagno, V; Lembo, D; Caviglioli, G

    2014-06-01

    A new nanoparticulate system for foscarnet delivery was prepared and evaluated. Nanoparticles were obtained by ionotropic gelation of chitosan induced by foscarnet itself, acting as an ionotropic agent in a manner similar to tripolyphosphate anion. A Doehlert design allowed finding the suitable experimental conditions. Nanoparticles were between 200 and 300nm in diameter (around 450nm after redispersion). Nanoparticle size increased after 5h, but no size increase was observed after 48h when nanoparticles were crosslinked with glutaraldehyde. Zeta potential values of noncrosslinked and crosslinked nanoparticles were between 20 and 25mV, while drug loading of noncrosslinked nanoparticles was about 40% w/w (55% w/w for crosslinked nanoparticles). Nanoparticle yield was around 25% w/w. Crosslinked nanoparticles showed a controlled drug release. Foscarnet released from nanoparticles maintained the antiviral activity of the free drug when tested in vitro against lung fibroblasts (HELF) cells infected with HCMV strain AD-169. Moreover, nanoparticles showed no toxicity on non-infected HELF cells. These nanoparticles may represent a delivery system that could improve the therapeutic effect of foscarnet.

  16. Synthesis, Photochemical and Photoinduced Antibacterial Activity Studies of meso-Tetra(pyren-1-yl)porphyrin and its Ni, Cu and Zn Complexes

    PubMed Central

    Zoltan, Tamara; Vargas, Franklin; Rivas, Carlos; López, Verónica; Perez, Jhackelym; Biasutto, Antonio

    2010-01-01

    The synthesis of the meso-tetra(pyren-1-yl)porphyrin (1) was successfully accomplished by means of the pyrrole condensation with pyrene-1-carb-aldehyde in acidic media. Its metallization was carried out in an almost quantitative yield to obtain the corresponding complexes of Ni(II) (2), Cu(II) (3) and Zn (4). Their photophysical properties such as fluorescence quantum yield and energy transfer to oxygen for an efficient generation of singlet oxygen were determined. Their photophysical and photochemical properties were compared with those of other similar porphyrin derivatives such as tetraphenylporphyrin and tetranaphthylporphyrin. Photochemical studies on their effectiveness as photosensitizer were carried out by means of the photoinduced oxidation of aromatic alcohols like α-naphthol to naphthoquinone. The antibacterial photoactivity assay for compounds 1–4 was testeted against Escherichia coli (ATCC 8739) and its proliferation and viability were measured by chemiluminescence. An efficient inactivation of E. coli was observed. This was more efficient for compounds 2 and 3, following the direct relationship to high generation of singlet oxygen by these compounds. PMID:21179316

  17. Green synthesis, spectroscopic investigation and photocatalytic activity of lead nanoparticles.

    PubMed

    Elango, Ganesh; Roopan, Selvaraj Mohana

    2015-03-15

    Most of researcher focused their research towards synthesize of nanoparticles by the method of applied chemical method which was one of the costliest method. We have focused cheapest and simplest method for the synthesizing of lead nanoparticles (Pb-NPs) using cocos nucifera L extract. The methanolic extract of cocos nucifera L was efficiently used as a reducing agent for synthesizing Pb-NPs. On treatment of lead acetate with cocos nucifera coir extracts, stable Pb-NPs were formed. The synthesized Pb-NPs were further confirmed by UV-visible spectroscopy, X-ray diffraction (XRD), Transmission electron microscope (TEM) and Energy Dispersive (EDAX) analysis. The secondary metabolites present in methanolic extract which can mainly act as a reducing and capping agents for the formation of Pb-NPs were identified by GC-MS. Anti-microbial activity for Pb-NPs against four pathogenic strain's such as Staphylococcus aureus, Escheria coli, Staphylococcus epidermis and Bacillus subtilis. Result states that Pb-NPs size was 47 nm and also shows good activity against S. aureus. Further we report on photocatalytic absorption of malachite green dye processed in short UV wavelength at 254 nm. UV spectral analysis showed peak absorbance at 613 nm with special reference to the excitation of surfaces plasmon vibration by Pb-NPs.

  18. Green synthesis, spectroscopic investigation and photocatalytic activity of lead nanoparticles

    NASA Astrophysics Data System (ADS)

    Elango, Ganesh; Roopan, Selvaraj Mohana

    2015-03-01

    Most of researcher focused their research towards synthesize of nanoparticles by the method of applied chemical method which was one of the costliest method. We have focused cheapest and simplest method for the synthesizing of lead nanoparticles (Pb-NPs) using cocos nucifera L extract. The methanolic extract of cocos nucifera L was efficiently used as a reducing agent for synthesizing Pb-NPs. On treatment of lead acetate with cocos nucifera coir extracts, stable Pb-NPs were formed. The synthesized Pb-NPs were further confirmed by UV-visible spectroscopy, X-ray diffraction (XRD), Transmission electron microscope (TEM) and Energy Dispersive (EDAX) analysis. The secondary metabolites present in methanolic extract which can mainly act as a reducing and capping agents for the formation of Pb-NPs were identified by GC-MS. Anti-microbial activity for Pb-NPs against four pathogenic strain's such as Staphylococcus aureus, Escheria coli, Staphylococcus epidermis and Bacillus subtilis. Result states that Pb-NPs size was 47 nm and also shows good activity against S. aureus. Further we report on photocatalytic absorption of malachite green dye processed in short UV wavelength at 254 nm. UV spectral analysis showed peak absorbance at 613 nm with special reference to the excitation of surfaces plasmon vibration by Pb-NPs.

  19. Silver colloid nanoparticles: synthesis, characterization, and their antibacterial activity.

    PubMed

    Panacek, Ales; Kvítek, Libor; Prucek, Robert; Kolar, Milan; Vecerova, Renata; Pizúrova, Nadezda; Sharma, Virender K; Nevecna, Tat'jana; Zboril, Radek

    2006-08-24

    A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented. In this synthesis, reduction of [Ag(NH(3))(2)](+) complex cation by four saccharides was performed. Four saccharides were used: two monosaccharides (glucose and galactose) and two disaccharides (maltose and lactose). The syntheses performed at various ammonia concentrations (0.005-0.20 mol L(-1)) and pH conditions (11.5-13.0) produced a wide range of particle sizes (25-450 nm) with narrow size distributions, especially at the lowest ammonia concentrations. The average size, size distribution, morphology, and structure of particles were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and UV/Visible absorption spectrophotometry. The influence of the saccharide structure (monosacharides versus disaccharides) on the size of silver particles is briefly discussed. The reduction of [Ag(NH(3))(2)](+) by maltose produced silver particles with a narrow size distribution with an average size of 25 nm, which showed high antimicrobial and bactericidal activity against Gram-positive and Gram-negative bacteria, including highly multiresistant strains such as methicillin-resistant Staphylococcus aureus. Antibacterial activity of silver nanoparticles was found to be dependent on the size of silver particles. A very low concentration of silver (as low as 1.69 mug/mL Ag) gave antibacterial performance.

  20. Silver nanoparticles-induced cytotoxicity requires ERK activation in human bladder carcinoma cells.

    PubMed

    Castiglioni, Sara; Cazzaniga, Alessandra; Perrotta, Cristiana; Maier, Jeanette A M

    2015-09-17

    Silver nanoparticles are toxic both in vitro and in vivo. We have investigated the possibility to exploit the cytotoxic potential of silver nanoparticles in T24 bladder carcinoma cells using both bare and PolyVinylPyrrolidone-coated silver nanoparticles. We show that the two types of silver nanoparticles promote morphological changes and cytoskeletal disorganization, are cytotoxic and induce cell death. These effects are due to the increased production of reactive oxygen species which are responsible, at least in part, for the sustained activation of ERK1/2. Indeed, both cytotoxicity and ERK1/2 activation are prevented by exposing the cells to the anti-oxidant N-acetylcysteine. Also blocking the ERK1/2 pathway with the MEK inhibitor PD98059 protects the cells from nanoparticles' cytotoxicity. Our findings suggest that ERK activation plays a role in silver nanoparticle-mediated cytotoxicity in T24 cells.

  1. Biosynthesis of silver nanoparticles using aqueous leaf extract of Thevetia peruviana Juss and its antimicrobial activities

    NASA Astrophysics Data System (ADS)

    Oluwaniyi, Omolara O.; Adegoke, Haleemat I.; Adesuji, Elijah T.; Alabi, Aderemi B.; Bodede, Sunday O.; Labulo, Ayomide H.; Oseghale, Charles O.

    2016-08-01

    Biosynthesizing of silver nanoparticles using microorganisms or various plant parts have proven more environmental friendly, cost-effective, energy saving and reproducible when compared to chemical and physical methods. This investigation demonstrated the plant-mediated synthesis of silver nanoparticles using the aqueous leaf extract of Thevetia peruviana. UV-Visible spectrophotometer was used to measure the surface plasmon resonance of the nanoparticles at 460 nm. Fourier Transform Infrared showed that the glycosidic -OH and carbonyl functional group present in extract were responsible for the reduction and stabilization of the silver nanoparticles. X ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy and Selected Area Electron Diffraction analyses were used to confirm the nature, morphology and shape of the nanoparticles. The silver nanoparticles are spherical in shape with average size of 18.1 nm. The synthesized silver nanoparticles showed activity against fungal pathogens and bacteria. The zone of inhibition observed in the antimicrobial study ranged between 10 and 20 mm.

  2. Bioinspired synthesis of highly stabilized silver nanoparticles using Ocimum tenuiflorum leaf extract and their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Patil, Rupali S.; Kokate, Mangesh R.; Kolekar, Sanjay S.

    2012-06-01

    Biosynthesis of nanoparticles is under exploration due to wide biomedical applications and research interest in nanotechnology. We herein reports bioinspired synthesis of silver nanoparticles with the aid of novel, non toxic ecofriendly biological material namely Ocimum tenuiflorum leaf extract. It acts as reducing as well as stabilizing agent. An intense surface plasmon resonance band at ˜450 nm in the UV-visible spectrum clearly reveals the formation of silver nanoparticles. The photoluminescence spectrum was recorded to study excitation and emission. TEM and PSD by dynamic light scattering studies showed that size of silver nanoparticles to be in range 25-40 nm. Face centered cubic structure of silver nanoparticles are confirmed by SAED pattern. The charge on synthesized silver nanoparticles was determined by zeta potential. The colloidal solution of silver nanoparticles were found to exhibit high antibacterial activity against three different strains of bacteria Escherichia coli (Gram negative), Corney bacterium (gram positive), Bacillus substilus (spore forming).

  3. Bioinspired synthesis of highly stabilized silver nanoparticles using Ocimum tenuiflorum leaf extract and their antibacterial activity.

    PubMed

    Patil, Rupali S; Kokate, Mangesh R; Kolekar, Sanjay S

    2012-06-01

    Biosynthesis of nanoparticles is under exploration due to wide biomedical applications and research interest in nanotechnology. We herein reports bioinspired synthesis of silver nanoparticles with the aid of novel, non toxic ecofriendly biological material namely Ocimum tenuiflorum leaf extract. It acts as reducing as well as stabilizing agent. An intense surface plasmon resonance band at ∼450 nm in the UV-visible spectrum clearly reveals the formation of silver nanoparticles. The photoluminescence spectrum was recorded to study excitation and emission. TEM and PSD by dynamic light scattering studies showed that size of silver nanoparticles to be in range 25-40 nm. Face centered cubic structure of silver nanoparticles are confirmed by SAED pattern. The charge on synthesized silver nanoparticles was determined by zeta potential. The colloidal solution of silver nanoparticles were found to exhibit high antibacterial activity against three different strains of bacteria Escherichia coli (Gram negative), Corney bacterium (gram positive), Bacillus substilus (spore forming).

  4. Nanoparticle Solutions for Printed Electronics

    DTIC Science & Technology

    2013-09-19

    titania , silica) were investigated in the production of complementary inks for complex devices. These were either obtained commercially in... titania nanoparticles, with the electrolyte or semiconducting polymer between. Unlike conventional photochemical cells, the cell under development does

  5. Biopolymer-stabilized Pt nanoparticles colloid: a highly active and recyclable catalyst for biphasic catalysis

    NASA Astrophysics Data System (ADS)

    Wang, Yujia; Shen, Yueyue; Qiu, Yunfei; Zhang, Ting; Liao, Yang; Zhao, Shilin; Ma, Jun; Mao, Hui

    2016-10-01

    Noble metal nanoparticles are promising candidates to replace conventional bulk counterparts owing to their high activity and selectivity. To enable catalyst recovery, noble metal nanoparticles are often supported onto solid matrices to prepare heterogeneous catalyst. Although recycle of noble metal nanoparticles is realized by heterogenization, a loss of activity is usually encountered. In the present investigation, Pt nanoparticles with tunable particle size (1.85-2.80 nm) were facilely prepared by using polyphenols as amphiphilic stabilizers. The as-prepared Pt nanoparticles colloid solution could be used as highly active catalyst in aqueous-organic biphasic catalysis. The phenolic hydroxyls of polyphenols could constrain Pt nanoparticles in aqueous phase, and simultaneously, the aromatic scaffold of polyphenols ensured effective interactions between substrates and Pt nanoparticles. As a consequence, the obtained polyphenols-stabilized Pt nanoparticles exhibited high activity and cycling stability in biphasic hydrogenation of a series of unsaturated compounds. Compared with conventional heterogeneous Pt-C and Pt-Al2O3 catalysts, polyphenols-stabilized Pt nanoparticles showed obvious advantage both in activity and cycling stability.

  6. Strain specificity in antimicrobial activity of silver and copper nanoparticles.

    PubMed

    Ruparelia, Jayesh P; Chatterjee, Arup Kumar; Duttagupta, Siddhartha P; Mukherji, Suparna

    2008-05-01

    The antimicrobial properties of silver and copper nanoparticles were investigated using Escherichia coli (four strains), Bacillus subtilis and Staphylococcus aureus (three strains). The average sizes of the silver and copper nanoparticles were 3 nm and 9 nm, respectively, as determined through transmission electron microscopy. Energy-dispersive X-ray spectra of silver and copper nanoparticles revealed that while silver was in its pure form, an oxide layer existed on the copper nanoparticles. The bactericidal effect of silver and copper nanoparticles were compared based on diameter of inhibition zone in disk diffusion tests and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of nanoparticles dispersed in batch cultures. Bacterial sensitivity to nanoparticles was found to vary depending on the microbial species. Disk diffusion studies with E. coli and S. aureus revealed greater effectiveness of the silver nanoparticles compared to the copper nanoparticles. B. subtilis depicted the highest sensitivity to nanoparticles compared to the other strains and was more adversely affected by the copper nanoparticles. Good correlation was observed between MIC and MBC (r2=0.98) measured in liquid cultures. For copper nanoparticles a good negative correlation was observed between the inhibition zone observed in disk diffusion test and MIC/MBC determined based on liquid cultures with the various strains (r2=-0.75). Although strain-specific variation in MIC/MBC was negligible for S. aureus, some strain-specific variation was observed for E. coli.

  7. Activation of Latent HIV Using Drug-loaded Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kovochich, Michael

    Antiretroviral therapy is currently only capable of controlling human immunodeficiency virus (HIV) replication, rather than completely eradicating virus from patients. This is due in part to the establishment of a latent virus reservoir in resting CD4+ T-cells, which persists even in the presence of highly active antiretroviral therapy (HAART). It is thought that forced activation of latently infected cells could induce virus production, allowing targeting of the cell by the immune response. A variety of molecules are able to stimulate HIV from latency. However, no tested purging strategy has proven capable of eliminating the infection completely or preventing viral rebound if therapy is stopped. Hence, novel latency activation approaches are required. Nanoparticles can offer several advantages over more traditional drug delivery methods, including improved drug solubility, stability, and the ability to simultaneously target multiple different molecules to particular cell or tissue types. Here we describe the development of a novel lipid nanoparticle with the protein kinase C activator bryostatin-2 incorporated (LNP-Bry). These particles can target, activate primary human CD4+ T-cells, and stimulate latent virus production from human T-cell lines in vitro and from latently infected cells in a humanized mouse model ex vivo. This activation was synergistically enhanced by the histone deacetylase inhibitor (HDACi) sodium butyrate. Furthermore, LNP-Bry can also be loaded with the protease inhibitor nelfinavir (LNP-Bry-Nel), producing a particle capable of both activating latent virus and inhibiting viral spread. LNP-Bry was further tested for its in vivo biodistribution in both wild type mice (C57 black 6), as well as humanized mice (SCID-hu Thy/Liv, and bone marrow-liver-thymus [BLT]). LNP-Bry accumulated in the spleen and induced the early activation marker CD69 in wild type mice. Taken together, these data demonstrate the ability of nanotechnological approaches to

  8. Mycosynthesis of silver and gold nanoparticles: Optimization, characterization and antimicrobial activity against human pathogens.

    PubMed

    Balakumaran, M D; Ramachandran, R; Balashanmugam, P; Mukeshkumar, D J; Kalaichelvan, P T

    2016-01-01

    This study was aimed to isolate soil fungi from Kolli and Yercaud Hills, South India with the ultimate objective of producing antimicrobial nanoparticles. Among 65 fungi tested, the isolate, Bios PTK 6 extracellularly synthesized both silver and gold nanoparticles with good monodispersity. Under optimized reaction conditions, the strain Bios PTK 6 identified as Aspergillus terreus has produced extremely stable nanoparticles within 12h. These nanoparticles were characterized by UV-vis. spectrophotometer, HR-TEM, FTIR, XRD, EDX, SAED, ICP-AES and Zetasizer analyses. A. terreus synthesized 8-20 nm sized, spherical shaped silver nanoparticles whereas gold nanoparticles showed many interesting morphologies with a size of 10-50 nm. The presence and binding of proteins with nanoparticles was confirmed by FTIR study. Interestingly, the myco derived silver nanoparticles exhibited superior antimicrobial activity than the standard antibiotic, streptomycin except against Staphylococcus aureus and Bacillus subtilis. The leakage of intracellular components such as protein and nucleic acid demonstrated that silver nanoparticles damage the bacterial cells by formation of pores, which affects membrane permeability and finally leads to cell death. Further, presence of nanoparticles in the bacterial membrane and the breakage of cell wall were also observed using SEM. Thus, the obtained results clearly reveal that these antimicrobial nanoparticles could be explored as promising candidates for a variety of biomedical and pharmaceutical applications.

  9. Improved antimycobacterial activity of rifampin using solid lipid nanoparticles

    NASA Astrophysics Data System (ADS)

    Aboutaleb, Ehsan; Noori, Massoumeh; Gandomi, Narges; Atyabi, Fatemeh; Fazeli, Mohammad Reza; Jamalifar, Hossein; Dinarvand, Rassoul

    2012-10-01

    Rifampin (RIF) is one of the front-line drugs in therapy of tuberculosis (TB). The emergence of multidrug-resistant strains of mycobacteria has greatly contributed to the increased incidence of TB. Nano-based formulation of several antimicrobials has been shown to improve either antibacterial efficacy or pharmacokinetic behavior. In this study, RIF-loaded solid lipid nanoparticles (SLNs) were prepared by a modified microemulsion-based method and their particle size, zeta potential, encapsulation efficiency, morphology, and antibacterial activity against Mycobacterium fortuitum were evaluated. The resulting SLNs were spherical with diameter of about 100 nm, with low negative zeta potential, and an encapsulation efficiency of 82%. The formulation also sustained the drug release for 72 h. The antimycobacterial efficacy was greatly improved against M. fortuitum, and the minimum inhibitory concentration of drug-loaded SLNs was eight times less than free RIF. Drug-free SLNs and the ingredients showed no antibacterial effect. It can be concluded that as expected, solid lipid nanoparticles are promising vehicles for enhanced antimycobacterial effect of rifampin.

  10. The effect of temperature on antibacterial activity of biosynthesized silver nanoparticles.

    PubMed

    Pourali, Parastoo; Baserisalehi, Majid; Afsharnezhad, Sima; Behravan, Javad; Ganjali, Rashin; Bahador, Nima; Arabzadeh, Sepideh

    2013-02-01

    The purpose of this study was the evaluation of two different temperatures on antibacterial activity of the biosynthesized silver nanoparticles. 38 silver nanoparticles-producing bacteria were isolated from soil and identified. Biosynthesis of silver nanoparticles by these bacteria was verified through visible light spectrophotometry. Two strains were relatively active for production of silver nanoparticles. These strains were subjected for molecular identification and recognized as Bacillus sp. and Acinetobacter schindleri. In the present study, the effect of temperatures was evaluated on structure and antimicrobial properties of the silver nanoparrticles by transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and antimicrobial Agar well diffusion methods. The silver nanoparticles showed antibacterial activity against all the pathogenic bacteria; however, this property was lost after treatment of the silver nanoparticles by high temperatures (100 and 300 °C). TEM images showed that the average sizes of heated silver nanoparticles were >100 nm. However, these were <100 nm for non-heated silver nanoparticles. Although, XRD patterns showed the crystalline structure of heated silver nanoparticles, their antibacterial activities were less. This was possible because of the sizes and accordingly less penetration of the particles into the bacterial cells. In addition, elimination of the capping agents by heat might be considered another reason.

  11. Effects of Internalized Gold Nanoparticles with Respect to Cytotoxicity and Invasion Activity in Lung Cancer Cells

    PubMed Central

    Guo, Zhirui; Liu, Ying; Shen, Yujie; Zhou, Ping; Lu, Xiang

    2014-01-01

    The effect of gold nanoparticles on lung cancer cells is not yet clear. In this study, we investigated the cytotoxicity and cell invasion activity of lung cancer cells after treatment with gold nanoparticles and showed that small gold nanoparticles can be endocytosed by lung cancer cells and that they facilitate cell invasion. The growth of A549 cells was inhibited after treatment with 5-nm gold nanoparticles, but cell invasion increased. Endocytosed gold nanoparticles (size, 10 nm) notably promoted the invasion activity of 95D cells. All these effects of gold nanoparticles were not seen after treatment with larger particles (20 and 40 nm). The enhanced invasion activity may be associated with the increased expression of matrix metalloproteinase 9 and intercellular adhesion molecule-1. In this study, we obtained evidence for the effect of gold nanoparticles on lung cancer cell invasion activity in vitro. Moreover, matrix metalloproteinase 9 and intercellular adhesion molecule-1, key modulators of cell invasion, were found to be regulated by gold nanoparticles. These data also demonstrate that the responses of the A549 and 95D cells to gold nanoparticles have a remarkable relationship with their unique size-dependent physiochemical properties. Therefore, this study provides a new perspective for cell biology research in nanomedicine. PMID:24901215

  12. Synthesis of silver nanoparticles with antibacterial activity using the lichen Parmotrema praesorediosum.

    PubMed

    Mie, Ropisah; Samsudin, Mohd Wahid; Din, Laily B; Ahmad, Azizan; Ibrahim, Nazlina; Adnan, Siti Noor Adnalizawati

    2014-01-01

    Development of a green chemistry process for the synthesis of silver nanoparticles has become a focus of interest. This would offer numerous benefits, including ecofriendliness and compatibility for biomedical applications. Here we report the synthesis of silver nanoparticles from the reduction of silver nitrate and an aqueous extract of the lichen Parmotrema praesorediosum as a reductant as well as a stabilizer. The physical appearance of these silver nanoparticles was characterized using ultraviolet-visible spectroscopy, electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction techniques. The results show that silver nanoparticles synthesized using P. praesorediosum have an average particle size of 19 nm with a cubic structure. The antibacterial activity of the synthesized silver nanoparticles was tested against eight micro-organisms using the disk diffusion method. The results reveal that silver nanoparticles synthesized using P. praesorediosum have potential antibacterial activity against Gram-negative bacteria.

  13. Electrosprayed core-shell polymer-lipid nanoparticles for active component delivery.

    PubMed

    Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan

    2013-11-22

    A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core-shell polymer-lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core-shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core-shell form.

  14. Opuntia ficus indica peel derived pectin mediated hydroxyapatite nanoparticles: Synthesis, spectral characterization, biological and antimicrobial activities

    NASA Astrophysics Data System (ADS)

    Gopi, D.; Kanimozhi, K.; Kavitha, L.

    2015-04-01

    In the present study, we have adapted a facile and efficient green route for the synthesis of HAP nanoparticles using pectin as a template which was extracted from the peel of prickly pear (Opuntia ficus indica) fruits. The concentration of pectin plays a major role in the behavior of crystallinity, purity, morphology as well as biological property of the as-synthesized HAP nanoparticles. The extracted pectin and the as-synthesized nanoparticles were characterized by various analytical techniques. The in vitro apatite formation on the surface of the as-synthesized nanoparticles in simulated body fluid (SBF) for various days showed an enhanced bioactivity. Also, the antimicrobial activity was investigated using various microorganisms. All the results revealed the formation of pure, low crystalline and discrete granular like HAP nanoparticles of size around 25 nm with enhanced biological and antimicrobial activities. Hence the as-synthesized nanoparticles can act as a better bone regenerating material in the field of biomedicine.

  15. Electrosprayed core-shell polymer-lipid nanoparticles for active component delivery

    NASA Astrophysics Data System (ADS)

    Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan

    2013-11-01

    A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core-shell polymer-lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core-shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core-shell form.

  16. Opuntia ficus indica peel derived pectin mediated hydroxyapatite nanoparticles: synthesis, spectral characterization, biological and antimicrobial activities.

    PubMed

    Gopi, D; Kanimozhi, K; Kavitha, L

    2015-04-15

    In the present study, we have adapted a facile and efficient green route for the synthesis of HAP nanoparticles using pectin as a template which was extracted from the peel of prickly pear (Opuntia ficus indica) fruits. The concentration of pectin plays a major role in the behavior of crystallinity, purity, morphology as well as biological property of the as-synthesized HAP nanoparticles. The extracted pectin and the as-synthesized nanoparticles were characterized by various analytical techniques. The in vitro apatite formation on the surface of the as-synthesized nanoparticles in simulated body fluid (SBF) for various days showed an enhanced bioactivity. Also, the antimicrobial activity was investigated using various microorganisms. All the results revealed the formation of pure, low crystalline and discrete granular like HAP nanoparticles of size around 25 nm with enhanced biological and antimicrobial activities. Hence the as-synthesized nanoparticles can act as a better bone regenerating material in the field of biomedicine.

  17. Synthesis of silver nanoparticles with antibacterial activity using the lichen Parmotrema praesorediosum

    PubMed Central

    Mie, Ropisah; Samsudin, Mohd Wahid; Din, Laily B; Ahmad, Azizan; Ibrahim, Nazlina; Adnan, Siti Noor Adnalizawati

    2014-01-01

    Development of a green chemistry process for the synthesis of silver nanoparticles has become a focus of interest. This would offer numerous benefits, including ecofriendliness and compatibility for biomedical applications. Here we report the synthesis of silver nanoparticles from the reduction of silver nitrate and an aqueous extract of the lichen Parmotrema praesorediosum as a reductant as well as a stabilizer. The physical appearance of these silver nanoparticles was characterized using ultraviolet-visible spectroscopy, electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction techniques. The results show that silver nanoparticles synthesized using P. praesorediosum have an average particle size of 19 nm with a cubic structure. The antibacterial activity of the synthesized silver nanoparticles was tested against eight micro-organisms using the disk diffusion method. The results reveal that silver nanoparticles synthesized using P. praesorediosum have potential antibacterial activity against Gram-negative bacteria. PMID:24379670

  18. Synthesis of 1-dodecanethiol-capped Ag nanoparticles and their high catalytic activity

    NASA Astrophysics Data System (ADS)

    Zhang, Danhui; Yang, Youbo

    2017-01-01

    Silver nanoparticles, which were produced by the borohydride reduction of silver nitrate, were stabilized by means of 1-dodecanethiol providing sulfur atom in two-phase system involving water and organic solvent (such as toluene, chloroform and hexane). Different organic solvent played a major role in the particle size of silver nanoparticles. These silver nanoparticles synthesized in the three different organic solvent were characterized by X-ray Diffraction, transmission electron microscopy and ultraviolet-visible absorption spectroscopy. The results indicate that the particles size of silver nanoparticles formed in three organic solvents was different. Furthermore, 1-dodecanethiol-capped silver nanoparticles were found to serve as effective catalysts to activate the reduction of 4-nitrophenol (4NP) in the presence of NaBH4, where the size of silver nanoparticles played the determining role in catalytic activity.

  19. Biocompatibility selenium nanoparticles with an intrinsic oxidase-like activity

    NASA Astrophysics Data System (ADS)

    Guo, Leilei; Huang, Kaixun; Liu, Hongmei

    2016-03-01

    Selenium nanoparticles (SeNPs) are considered to be the new selenium supplement forms with high biological activity and low toxicity; however, the molecular mechanism by which SeNPs exert the biological function is unclear. Here, we reported that biocompatibility SeNPs possessed intrinsic oxidase-like activity. Using Na2SeO3 as a precursor and glutathione as a reductant, biocompatibility SeNPs were synthesized by the wet chemical reduction method in the presence of bovine serum albumin (BSA). The results of structure characterization revealed that synthesized SeNPs were amorphous red elementary selenium with spherical morphology, and ranged in size from 25 to 70 nm size with a narrow distribution (41.4 ± 6.7 nm). The oxidase-like activity of the as-synthesized SeNPs was tested with 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. The results indicated that SeNPs could catalyze the oxidization of TMB by dissolved oxygen. These SeNPs showed an optimum catalytic activity at pH 4 and 30 °C, and the oxidase-like activity was higher as the concentration of SeNPs increased and the size of SeNPs decreased. The Michaelis constant ( K m) values and maximal reaction velocity ( V max) of the SeNPs for TMB oxidation were 0.0083 mol/L and 3.042 μmol/L min, respectively.

  20. The study of the antimicrobial activity of colloidal solutions of silver nanoparticles prepared using food stabilizers.

    PubMed

    Balandin, G V; Suvorov, O A; Shaburova, L N; Podkopaev, D O; Frolova, Yu V; Ermolaeva, G A

    2015-06-01

    The bactericidal effect of colloidal solutions of silver nanoparticles based on food stabilizers, gum arabic and chitosan, against bacterial cultures of microorganisms in food production is described. The antibacterial activity of nanotechnology products containing different amounts of stabilizing additives when applied to solid pH-neutral substrates is studied. For its evaluation a method making it possible to take into account the capability of nanoparticles to diffuse in solid media was applied. Minimal inhibitory concentrations of nanoparticles used against Erwinia herbicola, Pseudomonas fluorescens, Bacillus subtilis, Sarcina flava were found. A suggestion was made concerning the influence of the spatial structure of bacteria on the antibacterial activity of colloidal solutions of silver nanoparticles. The data concerning the antibacterial activity and minimal inhibiting concentrations of nanoparticles may be used for development of products suppressing activity of microorganisms hazardous for food production.

  1. Surface enhanced Raman scattering, antibacterial and antifungal active triangular gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Smitha, S. L.; Gopchandran, K. G.

    2013-02-01

    Shape controlled syntheses of gold nanoparticles have attracted a great deal of attention as their optical, electronic, magnetic and biological properties are strongly dependent on the size and shape of the particles. Here is a report on the surface enhanced Raman scattering (SERS) activity of Cinnamomum zeylanicum leaf broth reduced gold nanoparticles consisting of triangular and spherical like particles, using 2-aminothiophenol (2-ATP) and crystal violet (CV) as probe molecules. Nanoparticles prepared with a minimum leaf broth concentration, having a greater number of triangular like particles exhibit a SERS activity of the order of 107. The synthesized nanoparticles exhibit efficient antibacterial activity against the tested gram negative bacterium Escherichia coli and gram positive bacterium Staphylococcus aureus. Investigations on the antifungal activity of the synthesized nanoparticles against Aspergillus niger and Fusarium oxysporum positive is also discussed.

  2. Carbon nanotubes-dispersed TiO{sub 2} nanoparticles with their enhanced photocatalytic activity

    SciTech Connect

    Liu, Bo; Xu, Youfeng; Cui, Jing; Wang, Sheng; Wang, Tao

    2014-11-15

    Graphical abstract: Carbon nanotubes-dispersed TiO{sub 2} nanoparticles with their enhanced photocatalytic activity. - Abstract: A novel carbon nanotubes (CNTs)-dispersed route is used to prepare high-activity titanium dioxide nanoparticles (TiO{sub 2}). Field-emission scanning electron microscopy and transmission electron microscopy reveals that the irregular TiO{sub 2} nanoparticles with diameters of 10–20 nm are highly dispersed. X-ray diffraction and specific surface area measurement show that high-activity anatase crystal is formed and the specific surface area of TiO{sub 2} nanoparticles is 147.36 m{sup 2}/g. The photoactivity of TiO{sub 2} was tested by photodegradation of Rhodamine B. The result shows that the photocatalytic activity of TiO{sub 2} nanoparticles prepared by the CNTs-dispersed route is three times higher than that by conventional hydrothermal treatment.

  3. Strategy for introducing antibacterial activity under ambient illumination in titania nanoparticles

    NASA Astrophysics Data System (ADS)

    Hsu, Alexander; Liu, Fangzhou; Leung, Yu Hang; Ma, Angel P. Y.; Djurišić, Aleksandra B.; Leung, Frederick C. C.

    2014-03-01

    Titanium dioxide (TiO2) is a wide bandgap (~3.4 eV) semiconductor material which is commonly used as a photocatalyst and antibacterial material. UV illumination with energy similar to the bandgap is often needed to make the material active. It would be favorable for practical applications, if its action can also be activated under ambient. Recently, robust antibacterial action was demonstrated on ZnO nanoparticles under ambient illumination. In this study, we demonstrated robust antibacterial activity of TiO2 nanoparticles induced by annealing under ambient illumination. It was found that the antibacterial activity could be significantly changed by tuning the annealing temperatures and using different crucibles containing the nanoparticles. Bacterium Escherichia coli was used as the model organism in the test. It was observed that although no significant antibacterial activity was observed on the starting material (untreated commercial TiO2 nanoparticles), the activity increases significantly if the nanoparticles were annealed above 650 °C with crucible lined with copper foil. The survival rate of E. coli bacteria approaches to zero if the nanoparticles annealing temperature reaches 850 °C. Under optimized conditions, three different titania nanoparticle samples exhibited antibacterial activity under ambient illumination. This work sheds light on the development of ambient-active antibacterial coating and in particular, on the modification of any TiO2 material to become ambient-active with a suitable treatment.

  4. Support nanostructure boosts oxygen transfer to catalytically active platinum nanoparticles.

    PubMed

    Vayssilov, Georgi N; Lykhach, Yaroslava; Migani, Annapaola; Staudt, Thorsten; Petrova, Galina P; Tsud, Nataliya; Skála, Tomáš; Bruix, Albert; Illas, Francesc; Prince, Kevin C; Matolín, Vladimír; Neyman, Konstantin M; Libuda, Jörg

    2011-04-01

    Interactions of metal particles with oxide supports can radically enhance the performance of supported catalysts. At the microscopic level, the details of such metal-oxide interactions usually remain obscure. This study identifies two types of oxidative metal-oxide interaction on well-defined models of technologically important Pt-ceria catalysts: (1) electron transfer from the Pt nanoparticle to the support, and (2) oxygen transfer from ceria to Pt. The electron transfer is favourable on ceria supports, irrespective of their morphology. Remarkably, the oxygen transfer is shown to require the presence of nanostructured ceria in close contact with Pt and, thus, is inherently a nanoscale effect. Our findings enable us to detail the formation mechanism of the catalytically indispensable Pt-O species on ceria and to elucidate the extraordinary structure-activity dependence of ceria-based catalysts in general.

  5. Enhanced immunomodulatory activity of gelatin-encapsulated Rubus coreanus Miquel nanoparticles.

    PubMed

    Seo, Yong Chang; Choi, Woon Yong; Lee, Choon Geun; Cha, Seon Woo; Kim, Young Ock; Kim, Jin-Chul; Drummen, Gregor P C; Lee, Hyeon Yong

    2011-01-01

    The aim of this work was to investigate the immunomodulatory activities of Rubus coreanus Miquel extract-loaded gelatin nanoparticles. The mean size of the produced nanoparticles was 143 ± 18 nm with a bandwidth of 76 nm in the size distribution and a maximum size of ~200 nm, which allows effective nanoparticle uptake by cells. Confocal imaging confirmed this, since the nanoparticles were internalized within 30 min and heterogeneously distributed throughout the cell. Zeta-potential measurements showed that from pH = 5 onwards, the nanoparticles were highly negatively charged, which prevents agglomeration to clusters by electrostatic repulsion. This was confirmed by TEM imaging, which showed a well dispersed colloidal solution. The encapsulation efficiency was nearly 60%, which is higher than for other components encapsulated in gelatin nanoparticles. Measurements of immune modulation in immune cells showed a significant effect by the crude extract, which was only topped by the nanoparticles containing the extract. Proliferation of B-, T- and NK cells was notably enhanced by Rubus coreanus-gelatin nanoparticles and in general ~2-3 times higher than control and on average ~2 times higher than ferulic acid. R. coreanus-gelatin nanoparticles induced cytokine secretion (IL-6 and TNF-α) from B- and T-cells on average at a ~2-3 times higher rate compared with the extract and ferulic acid. In vivo immunomodulatory activity in mice fed with R. coreanus-gelatin nanoparticles at 1 mL/g body weight showed a ~5 times higher antibody production compared to control, a ~1.3 times higher production compared to the extract only, and a ~1.6 times higher production compared to ferulic acid. Overall, our results suggest that gelatin nanoparticles represent an excellent transport vehicle for Rubus coreanus extract and extracts from other plants generally used in traditional Asian medicine. Such nanoparticles ensure a high local concentration that results in enhancement of immune cell

  6. Synthesis and characterization of dextran-capped silver nanoparticles with enhanced antibacterial activity.

    PubMed

    Yang, Guili; Lin, Qiuxia; Wang, Chunren; Li, Junjie; Wang, Jian; Zhou, Jin; Wang, Yan; Wang, Changyong

    2012-05-01

    Dextran-capped silver nanoparticles were synthesized by reducing silver nitrate with NaBH4 in the presence of dextran as capping agent. The characters of silver nanoparticles were investigated using UV-Vis spectrophotometer, nano-grainsize analyzer, X-ray diffraction, and transmission electron microscopy. Results showed that the silver nanoparticles capped with dextran were in uniform shape and narrow size distribution. Moreover, compared with polyvinylpyrrolidone (PVP)-capped silver nanoparticles, the dextran-capped ones possessed better stability. Antibacterial tests of these silver nanoparticles were carried out for Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Results suggested that the dextran-capped silver nanoparticles had high antibacterial activity against both Gram-positive and Gram-negative bacteria. In addition, the cytotoxicity in vitro of the dextran-capped silver nanoparticles was investigated using mouse fibrosarcoma cells (L929). The toxicity was evaluated by the changes of cell morphology and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. Results indicated that these silver nanoparticles had slight effect on the survival and proliferation of L-929 cells at their minimal inhibitory concentration (MIC). After modified by dextran, the physiochemical properties of the silver nanoparticles had been improved. We anticipated that these dextran-capped silver nanoparticles could be integrated into systems for biological and pharmaceutical applications.

  7. Palladium and Platinum Nanoparticles Attenuate Aging-Like Skin Atrophy via Antioxidant Activity in Mice

    PubMed Central

    Shibuya, Shuichi; Ozawa, Yusuke; Watanabe, Kenji; Izuo, Naotaka; Toda, Toshihiko; Yokote, Koutaro; Shimizu, Takahiko

    2014-01-01

    Cu-Zn superoxide dismutase (Sod1) loss causes a redox imbalance as it leads to excess superoxide generation, which results in the appearance of various aging-related phenotypes, including skin atrophy. Noble metal nanoparticles, such as palladium (Pd) and platinum (Pt) nanoparticles, are considered to function as antioxidants due to their strong catalytic activity. In Japan, a mixture of Pd and Pt nanoparticles called PAPLAL has been used to treat chronic diseases over the past 60 years. In the present study, we investigated the protective effects of PAPLAL against aging-related skin pathologies in mice. Transdermal PAPLAL treatment reversed skin thinning associated with increased lipid peroxidation in Sod1−/− mice. Furthermore, PAPLAL normalized the gene expression levels of Col1a1, Mmp2, Has2, Tnf-α, Il-6, and p53 in the skin of the Sod1−/− mice. Pt nanoparticles exhibited marked SOD and catalase activity, while Pd nanoparticles only displayed weak SOD and catalase activity in vitro. Although the SOD and catalase activity of the Pt nanoparticles significantly declined after they had been oxidized in air, a mixture of Pd and Pt nanoparticles continued to exhibit SOD and catalase activity after oxidation. Importantly, a mixture of Pd and Pt nanoparticles with a molar ratio of 3 or 4 to 1 continued to exhibit SOD and catalase activity after oxidation, indicating that Pd nanoparticles prevent the oxidative deterioration of Pt nanoparticles. These findings indicate that PAPLAL stably suppresses intrinsic superoxide generation both in vivo and in vitro via SOD and catalase activity. PAPLAL is a potentially powerful tool for the treatment of aging-related skin diseases caused by oxidative damage. PMID:25333617

  8. Palladium and platinum nanoparticles attenuate aging-like skin atrophy via antioxidant activity in mice.

    PubMed

    Shibuya, Shuichi; Ozawa, Yusuke; Watanabe, Kenji; Izuo, Naotaka; Toda, Toshihiko; Yokote, Koutaro; Shimizu, Takahiko

    2014-01-01

    Cu-Zn superoxide dismutase (Sod1) loss causes a redox imbalance as it leads to excess superoxide generation, which results in the appearance of various aging-related phenotypes, including skin atrophy. Noble metal nanoparticles, such as palladium (Pd) and platinum (Pt) nanoparticles, are considered to function as antioxidants due to their strong catalytic activity. In Japan, a mixture of Pd and Pt nanoparticles called PAPLAL has been used to treat chronic diseases over the past 60 years. In the present study, we investigated the protective effects of PAPLAL against aging-related skin pathologies in mice. Transdermal PAPLAL treatment reversed skin thinning associated with increased lipid peroxidation in Sod1-/- mice. Furthermore, PAPLAL normalized the gene expression levels of Col1a1, Mmp2, Has2, Tnf-α, Il-6, and p53 in the skin of the Sod1-/- mice. Pt nanoparticles exhibited marked SOD and catalase activity, while Pd nanoparticles only displayed weak SOD and catalase activity in vitro. Although the SOD and catalase activity of the Pt nanoparticles significantly declined after they had been oxidized in air, a mixture of Pd and Pt nanoparticles continued to exhibit SOD and catalase activity after oxidation. Importantly, a mixture of Pd and Pt nanoparticles with a molar ratio of 3 or 4 to 1 continued to exhibit SOD and catalase activity after oxidation, indicating that Pd nanoparticles prevent the oxidative deterioration of Pt nanoparticles. These findings indicate that PAPLAL stably suppresses intrinsic superoxide generation both in vivo and in vitro via SOD and catalase activity. PAPLAL is a potentially powerful tool for the treatment of aging-related skin diseases caused by oxidative damage.

  9. Intracellular synthesis of silver nanoparticle by actinobacteria and its antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Otari, S. V.; Patil, R. M.; Ghosh, S. J.; Thorat, N. D.; Pawar, S. H.

    2015-02-01

    Intracellular synthesis of silver nanoparticles (AgNPs) using Rhodococcus spp. is demonstrated. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier trans-form infrared spectroscopy, and transmission electron microscopy. Transmission electron microscopy study of microorganisms' revealed synthesis of nanoparticle was occurring inside the cell, in the cytoplasm. AgNPs ranged from 5 to 50 nm. Formed nanoparticles were stable in the colloidal solution due to presence of proteins on the surface. AgNPs showed excellent bactericidal and bacteriostatic activity against pathogenic microorganisms.

  10. Hydrous RuO2 nanoparticles as highly active electrocatalysts for hydrogen evolution reaction

    NASA Astrophysics Data System (ADS)

    Lee, Jooyoung; Sher Shah, Selim Arif; Yoo, Pil J.; Lim, Byungkwon

    2017-04-01

    This letter describes an aqueous-phase synthetic route to hydrous ruthenium oxide (RuO2) nanoparticles and their conversion into crystalline ones via a thermal annealing process. Electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were employed to characterize hydrous and crystalline RuO2 nanoparticles. The hydrous RuO2 nanoparticles exhibited higher activity for hydrogen evolution reaction than commercial Pt catalyst, while the crystalline RuO2 nanoparticles showed better performance for oxygen evolution reaction than IrO2 catalyst. With these hydrous and crystalline RuO2 catalysts, we were able to achieve highly efficient overall electrochemical water splitting.

  11. Green synthesis of rifampicin-loaded copper nanoparticles with enhanced antimicrobial activity.

    PubMed

    Woźniak-Budych, Marta J; Przysiecka, Łucja; Langer, Krzysztof; Peplińska, Barbara; Jarek, Marcin; Wiesner, Maciej; Nowaczyk, Grzegorz; Jurga, Stefan

    2017-03-01

    The antimicrobial properties of copper and rifampicin-loaded copper nanoparticles were investigated using four strains: Staphylococcus aureus, Escherichia coli, Bacillus pumilis and Pseudomonas fluorescens. Spherical-shaped copper nanoparticles were synthesized via green reduction method from the peppermint extract. It was found that adsorption of rifampicin on the copper nanosurface enhances its biological activity and prevents the development of resistance. The interactions between rifampicin-copper nanoparticles and bacteria cells were monitored using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). It was proven that loaded with rifampicin copper nanoparticles were able to damage the S. aureus cell membrane and facilitate the bacteria biofilm matrix disintegration. Moreover, the DNA decomposition of S. aureus treated with copper and rifampicin-copper nanoparticles was confirmed by agarose gel electrophoresis. The results obtained indicate that adsorption of rifampicin on the copper nanoparticles surface might provide the reduction of antibiotic dosage and prevent its adverse side effects.

  12. Efficient synthesis of silver nanoparticles from Prosopis juliflora leaf extract and its antimicrobial activity using sewage

    NASA Astrophysics Data System (ADS)

    Raja, K.; Saravanakumar, A.; Vijayakumar, R.

    2012-11-01

    In this paper, aqueous extract of fresh leaves of Prosopis juliflora was used for the synthesis of silver (Ag) nanoparticles. UV-Vis spectroscopy studies were carried out to asses silver nanoparticles formation within 5 min, scanning electron microscopic was used to characterize shape of the Ag nanoparticles, X-ray diffraction analysis confirms the nanoparticles as crystalline silver and facecentered cubic type and Fourier transform infra-red assed that shows biomolecule compounds which are responsible for reduction and capping material of silver nanoparticles. The anti microbial activity of silver nanoparticle was performed using sewage. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods.

  13. Efficient synthesis of silver nanoparticles from Prosopis juliflora leaf extract and its antimicrobial activity using sewage.

    PubMed

    Raja, K; Saravanakumar, A; Vijayakumar, R

    2012-11-01

    In this paper, aqueous extract of fresh leaves of Prosopis juliflora was used for the synthesis of silver (Ag) nanoparticles. UV-Vis spectroscopy studies were carried out to asses silver nanoparticles formation within 5 min, scanning electron microscopic was used to characterize shape of the Ag nanoparticles, X-ray diffraction analysis confirms the nanoparticles as crystalline silver and facecentered cubic type and Fourier transform infra-red assed that shows biomolecule compounds which are responsible for reduction and capping material of silver nanoparticles. The anti microbial activity of silver nanoparticle was performed using sewage. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods.

  14. Coleus aromaticus leaf extract mediated synthesis of silver nanoparticles and its bactericidal activity

    NASA Astrophysics Data System (ADS)

    Vanaja, Mahendran; Annadurai, Gurusamy

    2013-06-01

    The utilization of various plant resources for the biosynthesis of metallic nanoparticles is called green nanotechnology, and it does not utilize any harmful chemical protocols. The present study reports the plant-mediated synthesis of silver nanoparticles using the plant leaf extract of Coleus aromaticus, which acts as a reducing and capping agent. The silver nanoparticles were characterized by ultraviolet visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and the size of the silver nanoparticles is 44 nm. The bactericidal activity of the silver nanoparticles was carried out by disc diffusion method that showed high toxicity against Bacillus subtilis and Klebsiella planticola. Biosynthesis of silver nanoparticles by using plant resources is an eco-friendly, reliable process and suitable for large-scale production. Moreover, it is easy to handle and a rapid process when compared to chemical, physical, and microbe-mediated synthesis process.

  15. Synthesis of silver nanoparticles using A. indicum leaf extract and their antibacterial activity.

    PubMed

    Ashokkumar, S; Ravi, S; Kathiravan, V; Velmurugan, S

    2015-01-05

    Green synthesis of silver nanoparticles has been achieved using environmentally acceptable plant extract. It is observed that Abutilon indicum leaf extract can reduce silver ions into silver nanoparticles within 15 min of reaction time. The formation and stability of the reduced silver nanoparticles in the colloidal solution were monitored by UV-Vis spectrophotometer analysis. The mean particle diameter of silver nanoparticles was calculated from the XRD pattern. FT-IR spectra of the leaf extract after the development of nanoparticles are determined to allow identification of possible functional groups responsible for the conversion of metal ions to metal nanoparticles. The AgNPs thus obtained showed highly potent antibacterial activity toward Gram-positive (Staphyloccocus aureus and Bacillus subtilis) and Gram-negative (Salmonella typhi and Escherichia coli) microorganisms.

  16. The Role of Organic Capping Layers of Platinum Nanoparticles in Catalytic Activity of CO Oxidation

    SciTech Connect

    Park, Jeong Y.; Aliaga, Cesar; Renzas, J. Russell; Lee, Hyunjoo; Somorjai, Gabor A.

    2008-12-17

    We report the catalytic activity of colloid platinum nanoparticles synthesized with different organic capping layers. On the molecular scale, the porous organic layers have open spaces that permit the reactant and product molecules to reach the metal surface. We carried out CO oxidation on several platinum nanoparticle systems capped with various organic molecules to investigate the role of the capping agent on catalytic activity. Platinum colloid nanoparticles with four types of capping layer have been used: TTAB (Tetradecyltrimethylammonium Bromide), HDA (hexadecylamine), HDT (hexadecylthiol), and PVP (poly(vinylpyrrolidone)). The reactivity of the Pt nanoparticles varied by 30%, with higher activity on TTAB coated nanoparticles and lower activity on HDT, while the activation energy remained between 27-28 kcal/mol. In separate experiments, the organic capping layers were partially removed using ultraviolet light-ozone generation techniques, which resulted in increased catalytic activity due to the removal of some of the organic layers. These results indicate that the nature of chemical bonding between organic capping layers and nanoparticle surfaces plays a role in determining the catalytic activity of platinum colloid nanoparticles for carbon monoxide oxidation.

  17. Anomalous antibacterial activity and dye degradation by selenium doped ZnO nanoparticles.

    PubMed

    Dutta, Raj Kumar; Nenavathu, Bhavani Prasad; Talukdar, Soumita

    2014-02-01

    Selenium doped ZnO nanoparticles synthesized by mechanochemical method were spherically shaped of size distribution of 10.2±3.4 nm measured by transmission electron microscopy. Diffused reflectance spectroscopy revealed increase in the band gap, ranging between 3.47 eV and 3.63 eV due to Se doping in ZnO nanoparticles. The antibacterial activity of pristine and Se doped ZnO nanoparticles was attributed to ROS (reactive oxygen species) generation in culture media confirmed by TBARS assay. Compared to complete inhibition of growth by 0.45 mg/mL of pristine ZnO nanoparticles, the batches of 0.45 mg/mL of selenium doped ZnO nanoparticles exhibited only 51% inhibition of growth of Escherichia coli. The reduced antibacterial activity of selenium doped ZnO nanoparticles was attributed to two opposing factors, e.g., ROS generation for inhibition of growth, countered by sustaining growth of E. coli due to availability of Se micronutrients in culture media, confirmed by inductively coupled plasma mass spectrometer measurement. Higher ROS generation by selenium doped ZnO nanoparticles was attributed to creation of oxygen vacancies, confirmed from green emission peak observed at 565 nm. The impact of higher ROS generation by selenium doped ZnO nanoparticles was evident from enhanced photocatalytic degradation of trypan blue dye, than pristine ZnO nanoparticles.

  18. The Surface Modification and Antimicrobial Activity of Basic Magnesium Hypochlorite Nanoparticles.

    PubMed

    Xu, Lijian; Tang, Zengmin; Xu, Jianxiong; Zhang, Jide; Du, Jingjing; Li, Na

    2015-02-01

    The basic magnesium hypochlorite (BMH) nanoparticles were prepared by two micro-emulsion techniques and modified with sodium stearate. The influences of the main technical parameters such as the addition amount of sodium stearate, reaction temperature and reaction time on the Lipophilic degree (LD) of the modified BMH nanoparticles were investigated. The characteristics of the BMH nanoparticles were analysed by means of Malvern Instruments, transmission electron microscopy (TEM), water contact angle measurements, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). The antimicrobial activity of the modified BMH nanoparticles was investigated with the antibacterial circle test. The results showed that the average size of the BMH nanoparticles was 305 nm. The BMH nanoparticles had been successfully modified by sodium stearate and the LD of.the modified BMH nanoparticles was 8.4% when the addition amount of sodium stearate was 0.15 g, the reaction temperature was 10 °C and the reaction time was 5 h. The dispersibility and hydrophobicity of the modified BMH nanoparticles were improved and the contact angle was up to 103 °, the modified BMH nanoparticles still had excellent antimicrobial activity after modification.

  19. Biosynthesis and recovery of rod-shaped tellurium nanoparticles and their bactericidal activities

    SciTech Connect

    Zare, Bijan; Faramarzi, Mohammad Ali; Sepehrizadeh, Zargham; Shakibaie, Mojtaba; Rezaie, Sassan; Shahverdi, Ahmad Reza

    2012-11-15

    Highlights: ► Biosynthesis of rod shape tellurium nanoparticles with a hexagonal crystal structure. ► Extraction procedure for isolation of tellurium nanoparticles from Bacillus sp. BZ. ► Extracted tellurium nanoparticles have good bactericidal activity against some bacteria. -- Abstract: In this study, a tellurium-transforming Bacillus sp. BZ was isolated from the Caspian Sea in northern Iran. The isolate was identified by various tests and 16S rDNA analysis, and then used to prepare elemental tellurium nanoparticles. The isolate was subsequently used for the intracellular biosynthesis of elemental tellurium nanoparticles. The biogenic nanoparticles were released by liquid nitrogen and purified by an n-octyl alcohol water extraction system. The shape, size, and composition of the extracted nanoparticles were characterized. The transmission electron micrograph showed rod-shaped nanoparticles with dimensions of about 20 nm × 180 nm. The energy dispersive X-ray and X-ray diffraction spectra respectively demonstrated that the extracted nanoparticles consisted of only tellurium and have a hexagonal crystal structure. This is the first study to demonstrate a biological method for synthesizing rod-shaped elemental tellurium by a Bacillus sp., its extraction and its antibacterial activity against different clinical isolates.

  20. Green synthesis and nanotopography of heparin-reduced gold nanoparticles with enhanced anticoagulant activity.

    PubMed

    Kim, Hyun-Seok; Jun, Sang Hui; Koo, Yean Kyoung; Cho, Seonho; Park, Youmie

    2013-03-01

    This paper reports on the green synthesis of heparin-reduced gold nanoparticles and their nanotopography as studied with atomic force microscopy. The study also evaluated the anticoagulant activity of the newly prepared gold nanoparticles. The heparin-reduced gold nanoparticles were homogeneous, showing characteristic surface plasmon resonance bands of approximately 523-527 nm, and their shapes were mostly spherical and amorphous. The average diameter of the nanoparticles measured from atomic force microscopic images was either 20.26 +/- 3.35 nm or 40.85 +/- 8.95 nm depending on the different precursor salts and heparin concentrations. Atomic force microscopic images revealed that the topography of the heparin polymer aggregated when deposited onto mica, resembling a chain of mountains. This characteristic nanotopography of the heparin disappeared after the synthesis of the gold nanoparticles was performed. Interestingly, prolonged prothrombin time, thrombin time, and activated partial thromboplastin time were observed in the heparin-reduced gold nanoparticles when compared to a control heparin, suggesting the enhancement of anticoagulant activity in heparin-reduced gold nanoparticles. Hence, the green synthesis of gold nanoparticles with heparin using a simple reaction step could be a viable procedure for enhancing heparin's anticoagulant activity.

  1. Unique Gold Nanoparticle Aggregates as a Highly Active SERS Substrate

    SciTech Connect

    Schwartzberg, A M; Grant, C D; Wolcott, A; Talley, C E; Huser, T R; Bogomolni, R; Zhang, J Z

    2004-04-06

    A unique gold nanoparticle aggregate (GNA) system has been shown to be an excellent substrate for surface-enhanced Raman scattering (SERS) applications. Rhodamine 6G (R6G), a common molecule used for testing SERS activity on silver, but generally difficult to detect on gold substrates, has been found to readily bind to the GNA and exhibit strong SERS activity due to the unique surface chemistry afforded by sulfur species on the surface. This GNA system has yielded a large SERS enhancement of 10{sup 7}-10{sup 9} in bulk solution for R6G, on par with or greater than any previously reported gold SERS substrate. SERS activity has also been successfully demonstrated for several biological molecules including adenine, L-cysteine, L-lysine, and L-histidine for the first time on a gold SERS substrate, showing the potential of this GNA as a convenient and powerful SERS substrate for biomolecular detection. In addition, SERS spectrum of R6G on single aggregates has been measured. We have shown that the special surface properties of the GNA, in conjunction with strong near IR absorption, make it useful for SERS analysis of a wide variety of molecules.

  2. Reduction of selenite to elemental selenium nanoparticles by activated sludge.

    PubMed

    Jain, Rohan; Matassa, Silvio; Singh, Satyendra; van Hullebusch, Eric D; Esposito, Giovanni; Lens, Piet N L

    2016-01-01

    Total selenium removal by the activated sludge process, where selenite is reduced to colloidal elemental selenium nanoparticles (BioSeNPs) that remain entrapped in the activated sludge flocs, was studied. Total selenium removal efficiencies with glucose as electron donor (2.0 g chemical oxygen demand (COD) L(-1)) at neutral pH and 30 °C gave 2.9 and 6.8 times higher removal efficiencies as compared to the electron donors lactate and acetate, respectively. Total selenium removal efficiencies of 79 (±3) and 86 (±1) % were achieved in shake flasks and fed batch reactors, respectively, at dissolved oxygen (DO) concentrations above 4.0 mg L(-1) and 30 °C when fed with 172 mg L(-1) (1 mM) Na2SeO3 and 2.0 g L(-1) COD of glucose. Continuously operated reactors operating at neutral pH, 30 °C and a DO >3 mg L(-1) removed 33.98 and 36.65 mg of total selenium per gram of total suspended solids (TSS) at TSS concentrations of 1.3 and 3.0 g L(-1), respectively. However, selenite toxicity to the activated sludge led to failure of a continuously operating activated sludge reactor at the applied loading rates. This suggests that a higher hydraulic retention time (HRT) or different reactor configurations need to be applied for selenium-removing activated sludge processes. Graphical Abstract Scheme representing the possible mechanisms of selenite reduction at high and low DO levels in the activated sludge process.

  3. Dysregulation of Macrophage Activation Profiles by Engineered Nanoparticles

    PubMed Central

    Kodali, Vamsi; Littke, Matthew H.; Tilton, Susan C.; Teeguarden, Justin G.; Shi, Liang; Frevert, Charles W.; Wang, Wei; Pounds, Joel G.; Thrall, Brian D.

    2013-01-01

    Although the potential human health impacts from exposure to engineered nanoparticles (ENPs) are uncertain, past epidemiological studies have established correlations between exposure to ambient air pollution particulates and the incidence of pneumonia and lung infections. Using amorphous silica and superparamagnetic iron oxide (SPIO) as model high production volume ENPs, we examined how macrophage activation by bacterial lipopolysaccharide (LPS) or the lung pathogen Streptococcus pneumoniae is altered by ENP pre-treatment. Neither silica nor SPIO treatment elicited direct cytotoxic or pro-inflammatory effects in bone marrow-derived macrophages. However, pre-treatment of macrophages with SPIO caused extensive reprogramming of nearly 500 genes regulated in response to LPS challenge, hallmarked by exaggerated activation of oxidative stress response pathways and suppressed activation of both pro- and anti-inflammatory pathways. Silica pre-treatment altered regulation of only 67 genes, but there was strong correlation with gene sets affected by SPIO. Macrophages exposed to SPIO displayed a phenotype suggesting an impaired ability to transition from a M1 to M2-like activation state, characterized by suppressed IL-10 induction, enhanced TNFα production, and diminished phagocytic activity toward S. pneumoniae. Studies in macrophages deficient in scavenger receptor A (SR-A) showed SR-A participates in cell uptake of both the ENPs and S. pneumonia, and co-regulates the anti-inflammatory IL-10 pathway. Thus, mechanisms for dysregulation of innate immunity exist by virtue that common receptor recognition pathways are used by some ENPs and pathogenic bacteria, although the extent of transcriptional reprogramming of macrophage function depends on the physicochemical properties of the ENP after internalization. Our results also illustrate that biological effects of ENPs may be indirectly manifested only after challenging normal cell function. Nanotoxicology screening strategies

  4. Dysregulation of Macrophage Activation Profiles by Engineered Nanoparticles

    SciTech Connect

    Kodali, Vamsi; Littke, Matthew H.; Tilton, Susan C.; Teeguarden, Justin G.; Shi, Liang; Frevert, Charles W.; Wang, Wei; Pounds, Joel G.; Thrall, Brian D.

    2013-08-27

    Although the potential human health impacts from exposure to engineered nanoparticles (ENPs) are uncertain, past epidemiological studies have established correlations between exposure to ambient air pollution particulates and the incidence of pneumonia and lung infections. Using amorphous silica and superparamagnetic iron oxide (SPIO) as model high production volume ENPs, we examined how macrophage activation by bacterial lipopolysaccharide (LPS) or the lung pathogen Streptococcus pneumoniae is altered by ENP pretreatment. Neither silica nor SPIO treatment elicited direct cytotoxic or pro-inflammatory effects in bone marrow-derived macrophages. However, pretreatment of macrophages with SPIO caused extensive reprogramming of nearly 500 genes regulated in response to LPS challenge, hallmarked by exaggerated activation of oxidative stress response pathways and suppressed activation of both pro- and anti-inflammatory pathways. Silica pretreatment altered regulation of only 67 genes, but there was strong correlation with gene sets affected by SPIO. Macrophages exposed to SPIO displayed a phenotype suggesting an impaired ability to transition from an M1 to M2-like activation state, characterized by suppressed IL-10 induction, enhanced TNFα production, and diminished phagocytic activity toward S. pneumoniae. Studies in macrophages deficient in scavenger receptor A (SR-A) showed SR-A participates in cell uptake of both the ENPs and S. pneumonia and co-regulates the anti-inflammatory IL-10 pathway. Thus, mechanisms for dysregulation of innate immunity exist by virtue that common receptor recognition pathways are used by some ENPs and pathogenic bacteria, although the extent of transcriptional reprogramming of macrophage function depends on the physicochemical properties of the ENP after internalization. Our results also illustrate that biological effects of ENPs may be indirectly manifested only after challenging normal cell function. Finally, nanotoxicology screening

  5. Chemical synthesis and antibacterial activity of novel-shaped silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Van Dong, Pham; Ha, Chu Hoang; Binh, Le Tran; Kasbohm, Jörn

    2012-06-01

    Silver nanoparticles are useful for medical applications due to their strong antibacterial activity. The antibacterial activity can be tuned by controlling the size and shape of the prepared silver nanoparticles. In this work, silver nanoparticles with different sizes and shapes were synthesized by solution phase routes, and their interactions with Escherichia coli were studied. Triangular silver nanoprisms were prepared by the reduction of silver nitrate at room temperature in the presence of polyvinylpyrrolidone, sodium citrate, hydrogen peroxide and sodium borohydride. Spherical silver nanoparticles were also prepared using silver nitrate as metal precursor and sodium citrate as well as sodium borohydride as reducing agents. The morphologies and structures of the nanoparticles were characterized by transmission electron microscopy, UV-visible spectroscopy and X-ray diffraction. The results indicated that spherical silver nanoparticles were obtained with different average sizes of 4, 21 and 40 nm, respectively. The edged silver nanoprisms containing mainly {111} lattice planes were obtained in the range size of 25 to 400 nm. The antibacterial study revealed that the edged triangular silver nanoprisms with {111} lattice planes exhibited the strongest antibacterial property, compared with spherical nanoparticles. Our study demonstrated that triangular silver nanoprisms with sharp edges also display a good antibacterial activity in comparison to other shaped nanoparticles.

  6. Synthesis, characteristics and antimicrobial activity of ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Janaki, A. Chinnammal; Sailatha, E.; Gunasekaran, S.

    2015-06-01

    The utilization of various plant resources for the bio synthesis of metallic nano particles is called green technology and it does not utilize any harmful protocols. Present study focuses on the green synthesis of ZnO nano particles by Zinc Carbonate and utilizing the bio-components of powder extract of dry ginger rhizome (Zingiber officinale). The ZnO nano crystallites of average size range of 23-26 nm have been synthesized by rapid, simple and eco friendly method. Zinc oxide nano particles were characterized by using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the adsorption of surfactant molecules at the surface of ZnO nanoparticles and the presence of ZnO bonding. Antimicrobial activity of ZnO nano particles was done by well diffusion method against pathogenic organisms like Klebsiella pneumonia, Staphylococcus aureus and Candida albicans and Penicillium notatum. It is observed that the ZnO synthesized in the process has the efficient antimicrobial activity.

  7. Synthesis, characteristics and antimicrobial activity of ZnO nanoparticles.

    PubMed

    Janaki, A Chinnammal; Sailatha, E; Gunasekaran, S

    2015-06-05

    The utilization of various plant resources for the bio synthesis of metallic nano particles is called green technology and it does not utilize any harmful protocols. Present study focuses on the green synthesis of ZnO nano particles by Zinc Carbonate and utilizing the bio-components of powder extract of dry ginger rhizome (Zingiber officinale). The ZnO nano crystallites of average size range of 23-26 nm have been synthesized by rapid, simple and eco friendly method. Zinc oxide nano particles were characterized by using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the adsorption of surfactant molecules at the surface of ZnO nanoparticles and the presence of ZnO bonding. Antimicrobial activity of ZnO nano particles was done by well diffusion method against pathogenic organisms like Klebsiella pneumonia, Staphylococcus aureus and Candida albicans and Penicillium notatum. It is observed that the ZnO synthesized in the process has the efficient antimicrobial activity.

  8. Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity

    NASA Astrophysics Data System (ADS)

    Ashraf, Sumaira; Chatha, Mariyam Asghar; Ejaz, Wardah; Janjua, Hussnain Ahmed; Hussain, Irshad

    2014-10-01

    Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests.

  9. Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity

    PubMed Central

    2014-01-01

    Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests. PMID:25435831

  10. Evaluation of antioxidant and anticancer activity of copper oxide nanoparticles synthesized using medicinally important plant extracts.

    PubMed

    Rehana, Dilaveez; Mahendiran, D; Kumar, R Senthil; Rahiman, A Kalilur

    2017-03-10

    Copper oxide (CuO) nanoparticles were synthesized by green chemistry approach using different plant extracts obtained from the leaves of Azadirachta indica, Hibiscus rosa-sinensis, Murraya koenigii, Moringa oleifera and Tamarindus indica. In order to compare their efficiency, the same copper oxide nanoparticles was also synthesized by chemical method. Phytochemical screening of the leaf extracts showed the presence of carbohydrates, flavonoids, glycosides, phenolic compounds, saponins, tannins, proteins and amino acids. FT IR spectra confirmed the possible biomolecules responsible for the formation of copper oxide nanoparticles. The surface plasmon resonance absorption band at 220-235nm in the UV-vis spectra also supports the formation of copper oxide nanoparticles. XRD patterns revealed the monoclinic phase of the synthesized copper oxide nanoparticles. The average size, shape and the crystalline nature of the nanoparticles were determined by SEM, TEM and SAED analysis. EDX analysis confirmed the presence of elements in the synthesized nanoparticles. The antioxidant activity was evaluated by three different free radical scavenging assays. The cytotoxicity of copper oxide nanoparticles was evaluated against four cancer cell lines such as human breast (MCF-7), cervical (HeLa), epithelioma (Hep-2) and lung (A549), and one normal human dermal fibroblast (NHDF) cell line. The morphological changes were evaluated using Hoechst 33258 staining assay. Copper oxide nanoparticles synthesized by green method exhibited high antioxidant and cytotoxicity than that synthesized by chemical method.

  11. Natural lipid nanoparticles containing nimesulide: synthesis, characterization and in vivo antiedematogenic and antinociceptive activities.

    PubMed

    Raffin, Renata P; Lima, Amanda; Lorenzoni, Ricardo; Antonow, Michelli B; Turra, Cláudia; Alves, Marta P; Fagan, Solange B

    2012-04-01

    Lipid nanoparticles are drug delivery systems able to increase bioavailability of poorly soluble drugs. They can be prepared with different lipid materials, especially natural lipids. Shea butter is a natural lipid obtained from the Butyrospermum parkii seed and rich in oleic and stearic acids. Nimesulide is a COX 2 selective anti-inflammatory that is poorly soluble in water. The purpose of this study was to develop and characterize shea butter lipid nanoparticles using a new technique and evaluate the in vivo activity of these nanoparticles. Lipid nanoparticles were prepared by melting shea butter and mixing with an aqueous phase using a high shear mixer. The nanoparticles presented pH of 6.9 +/- 0.1, mean particle size of 90 nm and a narrow polydispersity (0.21). Zeta potential was around -20 mV and the encapsulation efficiency was 97.5%. Drug release was evaluated using dialysis bags and presented monoexponential profile with t50% of 4.80 h (free drug t50% was only 2.86 h). Antinociceptive activity was performed by the acetic acid model. Both nimesulide and nimesulide-loaded nanoparticles presented significant activity compared to the control. The in vivo anti-inflammatory activity was evaluated by paw edema and was statistically different for the nanoparticles containing nimesulide compared to free nimesulide, blank nanoparticles and saline. In conclusion, the use of shea butter as encapsulating lipid was very successful and allowed nanoparticles to be prepared with a very simple technique. The nanoparticles presented significant pharmacological effects that were not seen for free drug administration.

  12. Chemical kinetic and photochemical data for use in stratospheric modelling

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Stief, L. J.; Kaufman, F.; Golden, D. M.; Hampton, R. F.; Kurylo, M. J.; Margitan, J. J.; Molina, M. J.; Watson, R. T.

    1979-01-01

    An evaluated set of rate constants and photochemical cross sections were compiled for use in modelling stratospheric processes. The data are primarily relevant to the ozone layer, and its possible perturbation by anthropogenic activities. The evaluation is current to, approximately, January, 1979.

  13. A prospective, active haemovigilance study with combined cohort analysis of 19 175 transfusions of platelet components prepared with amotosalen–UVA photochemical treatment

    PubMed Central

    Knutson, F; Osselaer, J; Pierelli, L; Lozano, M; Cid, J; Tardivel, R; Garraud, O; Hervig, T; Domanovic, D; Cukjati, M; Gudmundson, S; Hjalmarsdottir, I B; Castrillo, A; Gonzalez, R; Brihante, D; Santos, M; Schlenke, P; Elliott, A; Lin, J-S; Tappe, D; Stassinopoulos, A; Green, J; Corash, L

    2015-01-01

    Background and Objectives A photochemical treatment process (PCT) utilizing amotosalen and UVA light (INTERCEPT™ Blood System) has been developed for inactivation of viruses, bacteria, parasites and leucocytes that can contaminate blood components intended for transfusion. The objective of this study was to further characterize the safety profile of INTERCEPT-treated platelet components (PCT-PLT) administered across a broad patient population. Materials and Methods This open-label, observational haemovigilance programme of PCT-PLT transfusions was conducted in 21 centres in 11 countries. All transfusions were monitored for adverse events within 24 h post-transfusion and for serious adverse events (SAEs) up to 7 days post-transfusion. All adverse events were assessed for severity (Grade 0–4), and causal relationship to PCT-PLT transfusion. Results Over the course of 7 years in the study centres, 4067 patients received 19 175 PCT-PLT transfusions. Adverse events were infrequent, and most were of Grade 1 severity. On a per-transfusion basis, 123 (0·6%) were classified an acute transfusion reaction (ATR) defined as an adverse event related to the transfusion. Among these ATRs, the most common were chills (77, 0·4%) and urticaria (41, 0·2%). Fourteen SAEs were reported, of which 2 were attributed to platelet transfusion (<0·1%). No case of transfusion-related acute lung injury, transfusion-associated graft-versus-host disease, transfusion-transmitted infection or death was attributed to the transfusion of PCT-PLT. Conclusion This longitudinal haemovigilance safety programme to monitor PCT-PLT transfusions demonstrated a low rate of ATRs, and a safety profile consistent with that previously reported for conventional platelet components. PMID:25981525

  14. The water-soluble Roussin's red ester acting as a potential photochemical NO-delivery agent: photolysis reactions, DNA cleavage and anticancer activity.

    PubMed

    Chang, Han-Hun; Huang, Hung-Jen; Ho, Yun-Lung; Wen, Yu-Der; Huang, Wei-Ning; Chiou, Show-Jen

    2009-08-28

    The water-soluble Roussin's red ester [(NO)(2)Fe(mu-SCH(2)CH(2)P(O)(CH(2)OH)(2))(2)Fe(NO)(2)] (1), a potential photochemical prodrug of an NO precursor, was synthesized from the reaction of HSCH(2)CH(2)P(O)(CH(2)OH)(2) (F) and [Fe(CO)(2)(NO)(2)]. The IR v(NO) stretching frequencies of complex 1 appear at 1759 (s), 1784 (s) and 1816 (w) cm(-1) in buffer (pH = 7.4). NO was released with a stoichiometry ratio Delta[NO]/Delta[1] = 3.6 +/- 0.2 when complex 1 was exposed to UV in deaerated aqueous phosphate buffer solution. Here light acts as an On/Off switch for NO release. Incubation of pBR322 supercoiled DNA with complex 1, followed by irradiation, produced DNA strand breakage. In contrast to the addition of carboxy-PTIO (NO radical scavenger), DNA strand breakage was not inhibited when the scavengers of hydroxyl radical and singlet oxygen were added. Complex 1 irradiated under a N(2) atmosphere exhibited the same cleavage efficiency as complex 1 irradiated under air. The results show that DNA strand cleavage efficiency depends on the concentration of complex 1, the pH value of the buffer, and the duration of the photolysis of complex 1. The conversion rate from supercoiled (SC form) to nicked circular (NC form) of complex 1 was 2.96 x 10(-2) s(-1). The results of a T4 ligase enzymatic assay reveals the nonhydrolytic DNA breakage mechanism. The NO-release ability of complexes 1, 2, and 3 follows the order 1 > 2 > 3. Upon UV-irradiation, complex 1 exhibits cytotoxicity against B16-F10 mouse melanoma cells.

  15. Chitosan Adhesive Films for Photochemical Tissue Bonding

    NASA Astrophysics Data System (ADS)

    Lauto, Antonio; Mawad, Damia; Barton, Matthew; Piller, Sabine C.; Longo, Leonardo

    2011-08-01

    Photochemical tissue bonding (PTB) is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB) between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Materials and Methods. Adhesive films, based on chitosan and containing ˜0.1wt% RB were manufactured and bonded to calf intestine by a solid state laser (wavelength = 532 nm, Fluence ˜110 J/cm2, spot size ˜5 mm). A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T) at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. Results and Conclusion. The RB-chitosan adhesive bonded firmly to the intestine (15±2 kPa, n = 31). The adhesion strength dropped to 0.5±0.1 kPa (n = 8) when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26 °C to 32 °C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase.

  16. Effect of architecture on the activity of glucose oxidase/horseradish peroxidase/carbon nanoparticle conjugates.

    PubMed

    Ciaurriz, Paula; Bravo, Ernesto; Hamad-Schifferli, Kimberly

    2014-01-15

    We investigate the activity of glucose oxidase (GOx) together with horseradish peroxidase (HRP) on carbon nanoparticles (CNPs). Because GOx activity relies on HRP, we probe how the arrangement of the enzymes on the CNPs affects enzymatic behavior. Colorimetric assays to probe activity found that the coupling strategy affects activity of the bienzyme-nanoparticle complex. GOx is more prone than HRP to denaturation on the CNP surface, where its activity is compromised, while HRP activity is enhanced when interfaced to the CNP. Thus, arrangements where HRP is directly on the surface of the CNP and GOx is not are more favorable for overall activity. Coverage also influenced activity of the bienzyme complex, but performing the conjugation in the presence of glucose did not improve GOx activity. These results show that the architecture of the assembly is an important factor in optimization of nanoparticle-protein interfaces.

  17. Comparative Evaluation of Nimesulide-Loaded Nanoparticles for Anticancer Activity Against Breast Cancer Cells.

    PubMed

    Sengel-Turk, Ceyda Tuba; Hascicek, Canan; Bakar, Filiz; Simsek, Elif

    2017-02-01

    Recent clinical and epidemiological researches have declared that non-steroidal anti-inflammatory agents may display as antineoplastic agents and indicate pro-apoptotic and antiproliferative effects on cancer cells. The major purpose of this research was to develop a novel poly(ethyleneglycol)-block-poly(ε-caprolactone) (PEG-b-PCL) nano-sized particles encapsulated with nimesulide (NMS), a selective COX-2 inhibitor, and to evaluate its anticancer activity against MCF-7 breast cancer cells. NMS-encapsulated PEG-b-PCL nanoparticles were fabricated using three different production techniques: (i) by emulsion-solvent evaporation using a high shear homogenizer, (ii) by emulsion-solvent evaporation using an ultrasonicator, and (iii) by nanoprecipitation. Nanoparticles were evaluated with respect to the entrapment efficiency, size characteristics, drug release rates, thermal behavior, cell viability assays, and apoptosis. The resulting nanoparticles were found to be spherical shapes with negative surface charges. The average diameter of all nanoparticles ranged between 148.5 and 307.2 nm. In vitro release profiles showed that all nanoparticles exhibited a biphasic release pattern. NMS-loaded PEG-b-PCL nanoparticles demonstrated significant anticancer activity against MCF-7 breast cancer cells in a dose-dependent manner, and the effects of nanoparticles on cell proliferation were significantly affected by the preparation techniques. The nanoparticles developed in this work displayed higher potential for the NMS delivery against breast cancer treatment for the future.

  18. Engineering nanofluid electrodes: controlling rheology and electrochemical activity of γ-Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Sen, Sujat; Moazzen, Elahe; Aryal, Shankar; Segre, Carlo U.; Timofeeva, Elena V.

    2015-11-01

    Nanofluid electrodes or nanoelectrofuels have significant potential in the field of flow batteries, as at high loadings of solid battery active nanoparticles, their energy density can be orders of magnitude higher than in traditional redox flow battery electrolytes. Nanofluid electrodes must have a manageable viscosity at high particle concentrations (i.e., easily pumpable) and exhibit good electrochemical activity toward charge and discharge reactions. Engineering of such nanofluid electrodes involves development of new and unique approaches to stabilization of nanoparticle suspensions. In this work, we demonstrate a surface modification approach that allows controlling the viscosity of nanofluids at high solid loading, while simultaneously retaining electrochemical activity of the nanoparticles. A scalable single step procedure for the surface grafting of small organic molecules onto iron (III) oxide nanoparticles (γ-Fe2O3, maghemite, 40-150 nm) is demonstrated. Modified iron oxide nanoparticles reported here have 5 wt% of the grafting moiety on the surface, which helps forming stable dispersions with up to 40 wt% of solid loading in alkali aqueous electrolytes with a maximum viscosity of 12 cP at room temperature. The maximum particle concentration achievable in the same electrolyte with pristine nanoparticles is 15 wt%. Electrochemical testing of the pristine and modified nanomaterials in the form of solid-casted electrodes showed a maximum reversible discharge capacity of 280 and 155 mAh/g, respectively, indicating that electrochemical activity of modified nanoparticles is partially suppressed due to the surface grafted moiety.

  19. A single-nanoparticle NO2 gas sensor constructed using active molecular plasmonics.

    PubMed

    Chen, Lichan; Wu, Bo; Guo, Longhua; Tey, Ruiwen; Huang, Youju; Kim, Dong-Hwan

    2015-01-25

    A single-nanoparticle plasmonic sensor for the sensitive detection of gas molecules (NO2) has been constructed. Taking advantage of active molecular plasmonics, the analyte selectively triggers a measurable spectral shift of ferrocene-modified single gold nanorods.

  20. Interference sources in ATP bioluminescence assay of silica nanoparticle toxicity to activated sludge.

    PubMed

    Sibag, Mark; Kim, Seung Hwan; Kim, Choah; Kim, Hee Jun; Cho, Jinwoo

    2015-06-01

    ATP measurement provides an overview of the general state of microbial activity, and thus it has proven useful for the evaluation of nanoparticle toxicity in activated sludge. ATP bioluminescence assay, however, is susceptible to interference by the components of activated sludge other than biomass. This paper presents the interference identified specific to the use of this assay after activated sludge respiration inhibition test of silica nanoparticles (OECD 209). We observed a high degree of interference (90%) in the presence of 100 mg/L silica nanoparticles and a low level of ATP being measured (0.01 μM); and 30% interference by the synthetic medium regardless of silica nanoparticle concentration and ATP level in the samples. ATP measurement in activated sludge with different MLSS concentrations revealed interference of high biomass content. In conclusion, silica nanoparticles, synthetic medium and activated sludge samples themselves interfere with ATP bioluminescence; this will need to be considered in the evaluation of silica nanoparticle toxicity to activated sludge when this type of assay is used.

  1. Ascorbyl palmitate-loaded chitosan nanoparticles: characteristic and polyphenol oxidase inhibitory activity.

    PubMed

    Kim, Mi Kyung; Lee, Ji-Soo; Kim, Kwang Yup; Lee, Hyeon Gyu

    2013-03-01

    The aim of this study was to produce ascorbyl palmitate (AP)-loaded nanoparticles in order to inhibit polyphenol oxidase (PPO) in bananas. AP-loaded chitosan nanoparticles were prepared using acetic acid and citric acid (denoted as CS/AA and CS/CA nanoparticles, respectively). As the initial AP concentration increases, the particle size significantly decreases, and the zeta potential, entrapment and loading efficiency significantly increases. The PPO inhibitory activity of AP was effectively improved when AP was nano-encapsulated by chitosan compared to no encapsulation. These results suggest that chitosan nano-encapsulation can be used to enhance the PPO inhibitory activity of AP.

  2. Improving antibacterial activity of Spathodea campanulata Beauv's water extract with copper nanoparticle on Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Masruri, Masruri; Baihaqi, Muchammad Abdi; Riyanto, Slamet; Srihardyastutie, Arie

    2017-03-01

    This finding reports an antibacterial activity of water extract from the stem bark of Spathodea campanulata Beauv by combining it to the copper nanoparticle. The strategy involves extraction, characterization, and evaluation of water extract of Spathodea campanulata Beauv as an antibacterial agent. Includes, its pre-mixture with copper nanoparticle. In short, antibacterial activity of the mixture of water extract and copper nanoparticle inhibit the growth of Staphylococcus aureus three times higher than that using water extract. The result significantly paves the way for further application of Spathodea campanulata stem bark waste as antibacterial materials.

  3. Development and Antibacterial Activity of Cashew Gum-Based Silver Nanoparticles

    PubMed Central

    Quelemes, Patrick V.; Araruna, Felipe B.; de Faria, Bruna E. F.; Kuckelhaus, Selma A. S.; da Silva, Durcilene A.; Mendonça, Ronaldo Z.; Eiras, Carla; dos S. Soares, Maria José; Leite, José Roberto S. A.

    2013-01-01

    The present study describes the development of a green synthesis of silver nanoparticles reduced and stabilized by exuded gum from Anacardium occidentale L. and evaluates in vitro their antibacterial and cytotoxic activities. Characterization of cashew gum-based silver nanoparticles (AgNPs) was carried out based on UV–Vis spectroscopy, transmission electron microscopy and dynamic light scattering analysis which revealed that the synthesized silver nanoparticles were spherical in shape, measuring about 4 nm in size with a uniform dispersal. AgNPs presented antibacterial activity, especially against Gram-negative bacteria, in concentrations where no significant cytotoxicity was observed. PMID:23455467

  4. Modulation of cardiomyocyte activity using pulsed laser irradiated gold nanoparticles

    PubMed Central

    Gentemann, Lara; Kalies, Stefan; Coffee, Michelle; Meyer, Heiko; Ripken, Tammo; Heisterkamp, Alexander; Zweigerdt, Robert; Heinemann, Dag

    2016-01-01

    Can photothermal gold nanoparticle mediated laser manipulation be applied to induce cardiac contraction? Based on our previous work, we present a novel concept of cell stimulation. A 532 nm picosecond laser was employed to heat gold nanoparticles on cardiomyocytes. This leads to calcium oscillations in the HL-1 cardiomyocyte cell line. As calcium is connected to the contractility, we aimed to alter the contraction rate of native and stem cell derived cardiomyocytes. A contraction rate increase was particularly observed in calcium containing buffer with neonatal rat cardiomyocytes. Consequently, the study provides conceptual ideas for a light based, nanoparticle mediated stimulation system. PMID:28101410

  5. Synthesis and antimicrobial activity of gold nanoparticle conjugates with cefotaxime

    NASA Astrophysics Data System (ADS)

    Titanova, Elena O.; Burygin, Gennady L.

    2016-04-01

    Gold nanoparticles (GNPs) have attracted significant interest as a novel platform for various applications to nanobiotechnology and biomedicine. The conjugates of GNPs with antibiotics and antibodies were also used for selective photothermal killing of protozoa and bacteria. Also the conjugates of some antibiotics with GNPs decreased the number of bacterial growing cells. In this work was made the procedure optimization for conjugation of cefotaxime (a third-generation cephalosporin antibiotic) with GNPs (15 nm) and we examined the antimicrobial properties of this conjugate to bacteria culture of E. coli K-12. Addition of cefotaxime solution to colloidal gold does not change their color and extinction spectrum. For physiologically active concentration of cefotaxime (3 μg/mL), it was shown that the optimum pH for the conjugation was more than 9.5. A partial aggregation of the GNPs in saline medium was observed at pH 6.5-7.5. The optimum concentration of K2CO3 for conjugation cefotaxime with GNPs-15 was 5 mM. The optimum concentration of cefotaxime was at 0.36 μg/mL. We found the inhibition of the growth of E. coli K12 upon application cefotaxime-GNP conjugates.

  6. Antibacterial activity of silver nanoparticles synthesized from serine.

    PubMed

    Jayaprakash, N; Judith Vijaya, J; John Kennedy, L; Priadharsini, K; Palani, P

    2015-04-01

    Silver nanoparticles (Ag NPs) were synthesized by a simple microwave irradiation method using polyvinyl pyrrolidone (PVP) as a capping agent and serine as a reducing agent. UV-Visible spectra were used to confirm the formation of Ag NPs by observing the surface plasmon resonance (SPR) band at 443nm. The emission spectrum of Ag NPs showed an emission band at 484nm. In the presence of microwave radiation, serine acts as a reducing agent, which was confirmed by Fourier transformed infrared (FT-IR) spectrum. High-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning electron microscopy (HR-SEM) were used to investigate the morphology of the synthesized sample. These images showed the sphere-like morphology. The elemental composition of the sample was determined by the energy dispersive X-ray analysis (EDX). Selected area electron diffraction (SAED) was used to find the crystalline nature of the Ag NPs. The electrochemical behavior of the synthesized Ag NPs was analyzed by the cyclic voltammetry (CV). Antibacterial experiments showed that the prepared Ag NPs showed relatively similar antibacterial activities, when compared with AgNO3 against Gram-positive and Gram-negative bacteria.

  7. Silver nanoparticles synthesised using plant extracts show strong antibacterial activity.

    PubMed

    Kumari, Avnesh; Guliani, Anika; Singla, Rubbel; Yadav, Ramdhan; Yadav, Sudesh Kumar

    2015-06-01

    In this study, three plants Populus alba, Hibiscus arboreus and Lantana camara were explored for the synthesis of silver nanoparticles (SNPs). The effect of reaction temperature and leaf extract (LE) concentration of P. alba, H. arboreus and L. camara was evaluated on the synthesis and size of SNPs. The SNPs were characterised by ultra-violet-visible spectroscopy, scanning electron microscopy and atomic force microscopy. The synthesis rate of SNPs was highest with LE of L. camara followed by H. arboreus and P. alba under similar conditions. L. camara LE showed maximum potential of smaller size SNPs synthesis, whereas bigger particles were formed by H. arboreous LE. The size and shape of L. camara LE synthesised SNPs were analysed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). TEM analysis revealed the formation of SNPs of average size 17±9.5 nm with 5% LE of L. camara. The SNPs synthesised by LE of L. camara showed strong antibacterial activity against Escherichia coli. The results document that desired size SNPs can be synthesised using these plant LEs at a particular temperature for applications in the biomedical field.

  8. Silver Nanoparticle Impregnated Bio-Based Activated Carbon with Enhanced Antimicrobial Activity

    NASA Astrophysics Data System (ADS)

    Selvakumar, R.; Suriyaraj, S. P.; Jayavignesh, V.; Swaminathan, K.

    2013-08-01

    The present study involves the production of silver nanoparticles using a novel yeast strain Saccharomyces cerevisiae BU-MBT CY-1 isolated from coconut cell sap. The biological reduction of silver nitrate by the isolate was deducted at various time intervals. The yeast cells after biological silver reduction were harvested and subjected to carbonization at 400°C for 1 h and its properties were analyzed using Fourier transform infra-red spectroscopy, X-ray diffraction, scanning electron microscope attached with energy dispersive spectroscopy and transmission electron microscopy. The average size of the silver nanoparticles present on the surface of the carbonized silver containing yeast cells (CSY) was 19 ± 9 nm. The carbonized control yeast cells (CCY) did not contain any particles on its surface. The carbonized silver nanoparticles containing yeast cells (CSY) were made into bioactive emulsion and tested for its efficacy against various pathogenic Gram positive and Gram negative bacteria. The antimicrobial activity studies indicated that CSY bioactive nanoemulsion was effective against Gram negative organisms than Gram positive organism.

  9. Fruit juice extract mediated synthesis of CeO2 nanoparticles for antibacterial and photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Reddy Yadav, L. S.; Manjunath, K.; Archana, B.; Madhu, C.; Raja Naika, H.; Nagabhushana, H.; Kavitha, C.; Nagaraju, G.

    2016-05-01

    Ceria ( CeO2 is a technologically important rare-earth material because of its unique properties and various engineering/biological applications. In the present work, cerium oxide nanoparticles have been prepared by a simple solution combustion method using watermelon juice as a novel combustible fuel. The structure and morphology of the synthesized CeO2 nanoparticles were analyzed using various analytical tools such as PXRD, FTIR, Raman, UV-Visible and SEM. PXRD pattern confirms that the prepared material is composed of cubic-phase cerium oxide nanoparticles. Photocatalytic degradation of Methylene blue dye using CeO2 nanoparticles shows 98% of degradation in UV irradiations. Furthermore the antibacterial properties of CeO2 nanoparticles were investigated by their bacterial activity against two bacterial strains using the agar well diffusion method.

  10. Biosynthesis of Silver Nanoparticles from Marine Seaweed Sargassum cinereum and their Antibacterial Activity.

    PubMed

    Mohandass, C; Vijayaraj, A S; Rajasabapathy, R; Satheeshbabu, S; Rao, S V; Shiva, C; De-Mello, I

    2013-09-01

    Seaweed extracts of Sargassum cinereum was used as a reducing agent in the eco-friendly extracellular synthesis of silver nanoparticles from an aqueous solution of silver nitrate (AgNO3). High conversion of silver ions to silver nanoparticles was achieved with a reaction temperature of 100(°) and a seaweed extract concentration of 10% with a residential time of 3 h. Formation of silver nanoparticles was characterised by spectrophotometry and the scanning electron microscope. The average particles size was ranging from 45 to 76 nm. Antimicrobial activities indicate the minimum inhibitory concentration of biologically synthesised nanoparticles tested against the pathogen Staphylococcus aureus with 2.5 μl (25 μg/disc). High inhibitions over the growth of Enterobacter aerogenes, Salmonella typhi and Proteus vulgaris were witnessed against the concentrations of 100 μg/disc. Promising potential and the future prospects of S. cinereum nanoparticles in pharmaceutical research are the highlights in this paper.

  11. Preparation of a novel silk microfiber covered by AgCl nanoparticles with antimicrobial activity.

    PubMed

    Xie, Qifan; Xu, Zongpu; Hu, Binhui; He, Xiuling; Zhu, Liangjun

    2017-03-01

    We prepared silk fibroin microfibers in which silver chloride (AgCl) nanoparticles were dispersed, by sequential dipping of microfibers obtained using alkaline hydrolysis in alternating solutions of silver nitrate and potassium chloride. Scanning and transmission electron microscopy showed an increase in nanoparticle size and quantity with increase in dipping cycles and solution concentration, but ultrasound irradiation did not affect nanoparticle formation. The presence of cubic AgCl crystals was confirmed by energy dispersive X-ray spectroscopy and X-ray diffractometry. Differential scanning calorimetry and Fourier transform infrared spectroscopy revealed that the nanoparticles do not affect the microfiber properties. The growth of Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria was inhibited by microfiber covered with AgCl nanoparticles. This antimicrobial activity allows to use microfiber as a reinforced or surface additive biomaterial. Microsc. Res. Tech. 80:272-279, 2017. © 2016 Wiley Periodicals, Inc.

  12. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity.

    PubMed

    Bindhu, M R; Umadevi, M

    2013-01-15

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

  13. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Bindhu, M. R.; Umadevi, M.

    2013-01-01

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

  14. Preparation of Pt-Ru-Ni ternary nanoparticles by microemulsion and electrocatalytic activity for methanol oxidation

    SciTech Connect

    Zhang Xin . E-mail: xzhang@stu.edu.cn; Zhang Feng; Guan Renfeng; Chan, K.-Y.

    2007-02-15

    Ternary platinum-ruthenium-nickel nanoparticles are prepared by water-in-oil reverse microemulsions of water/Triton X-100/propanol-2/cyclohexane. Nanoparticles formed in the microemulsions are characterized by transmission electron microscopy (TEM), electron diffraction (ED), X-ray diffractometry (XRD), energy dispersive X-ray analysis (EDX). These resulting materials showed a homogenous alloy structure, the mono-dispersion and an average diameter of 2.6 {+-} 0.3 nm with a narrow particle size distribution. The composition and particle size of ternary Pt-Ru-Ni nanoparticles can be controlled by adjusting the initial metal salt solution and preparation conditions. Pt-Ru-Ni ternary metallic nanoparticles showed an enhanced catalytic activity towards methanol oxidation compared to Pt-Ru bimetallic nanoparticles.

  15. Quercetin nanoparticles display antitumor activity via proliferation inhibition and apoptosis induction in liver cancer cells.

    PubMed

    Ren, Ke-Wei; Li, Ya-Hua; Wu, Gang; Ren, Jian-Zhuang; Lu, Hui-Bin; Li, Zong-Ming; Han, Xin-Wei

    2017-04-01

    Quercetin is a potent cancer therapeutic agent and dietary antioxidant present in fruit and vegetables. Quercetin prevents tumor proliferation by inducing cell cycle arrest and is a well known cancer therapeutic agent and autophagy mediator. Recent studies showed that drug delivery by nanoparticles have enhanced efficacy with reduced side effects. In this regard, gold-quercetin into poly(DL-lactide-co-glycolide) nanoparticles was examined. In this study, we explored the role and possible underlying mechanisms of quercetin nanoparticle in regulation of antitumor activity in liver cancer cells. Treatment with quercetin nanoparticle effectively inhibited the liver cancer cell proliferation, cell migration and colony formation, thus suppressing liver cancer progression. Quercetin nanoparticle also upregulated apoptosis markedly. Further study suggested that quercetin nanoparticle accelerated the cleavage of caspase-9, caspase-3, and induced the up-releasing of cytochrome c (Cyto-c), contributing to apoptosis in liver cancer cells. Quercetin nanoparticles also promoted telomerase reverse transcriptase (hTERT) inhibition through reducing AP-2β expression and decreasing its binding to hTERT promoter. In addition, quercetin nanoparticle had an inhibitory role in cyclooxygenase 2 (COX-2) via suppressing the NF-κB nuclear translocation and its binding to COX-2 promoter. Quercetin nanoparticle also inactivated Akt and ERK1/2 signaling pathway. Taken together, our results suggested that quercetin nanoparticle had an antitumor effect by inactivating caspase/Cyto-c pathway, suppressing AP-2β/hTERT, inhibiting NF-κB/COX-2 and impeding Akt/ERK1/2 signaling pathways. Our results provided new mechanistic basis for further investigation of quercetin nanoparticles to find potential therapeutic strategies and possible targets for liver cancer inhibition.

  16. Synthesis, spectroscopic characterization, photochemical and photophysical properties and biological activities of ruthenium complexes with mono- and bi-dentate histamine ligand.

    PubMed

    Cardoso, Carolina R; de Aguiar, Inara; Camilo, Mariana R; Lima, Márcia V S; Ito, Amando S; Baptista, Maurício S; Pavani, Christiane; Venâncio, Tiago; Carlos, Rose M

    2012-06-14

    The monodentate cis-[Ru(phen)(2)(hist)(2)](2+)1R and the bidentate cis-[Ru(phen)(2)(hist)](2+)2A complexes were prepared and characterized using spectroscopic ((1)H, ((1)H-(1)H)COSY and ((1)H-(13)C)HSQC NMR, UV-vis, luminescence) techniques. The complexes presented absorption and emission in the visible region, as well as a tri-exponential emission decay. The complexes are soluble in aqueous and non-aqueous solution with solubility in a buffer solution of pH 7.4 of 1.14 × 10(-3) mol L(-1) for (1R + 2A) and 6.43 × 10(-4) mol L(-1) for 2A and lipophilicity measured in an aqueous-octanol solution of -1.14 and -0.96, respectively. Photolysis in the visible region in CH(3)CN converted the starting complexes into cis-[Ru(phen)(2)(CH(3)CN)(2)](2+). Histamine photorelease was also observed in pure water and in the presence of BSA (1.0 × 10(-6) mol L(-1)). The bidentate coordination of the histamine to the ruthenium center in relation to the monodentate coordination increased the photosubstitution quantum yield by a factor of 3. Pharmacological studies showed that the complexes present a moderate inhibition of AChE with an IC(50) of 21 μmol L(-1) (referred to risvagtini, IC(50) 181 μmol L(-1) and galantamine IC(50) 0.006 μmol L(-1)) with no appreciable cytotoxicity toward to the HeLa cells (50% cell viability at 925 μmol L(-1)). Cell uptake of the complexes into HeLa cells was detected by fluorescence confocal microscopy. Overall, the observation of a luminescent complex that penetrates the cell wall and has low cytotoxicity, but is reactive photochemically, releasing histamine when irradiated with visible light, are interesting features for application of these complexes as phototherapeutic agents.

  17. Cerium Oxide Nanoparticles Reduce Microglial Activation and Neurodegenerative Events in Light Damaged Retina

    PubMed Central

    Fiorani, Lavinia; Passacantando, Maurizio; Santucci, Sandro; Di Marco, Stefano; Bisti, Silvia; Maccarone, Rita

    2015-01-01

    The first target of any therapy for retinal neurodegeneration is to slow down the progression of the disease and to maintain visual function. Cerium oxide or ceria nanoparticles reduce oxidative stress, which is known to play a pivotal role in neurodegeneration. Our aim was to investigate whether cerium oxide nanoparticles were able to mitigate neurodegeneration including microglial activation and related inflammatory processes induced by exposure to high intensity light. Cerium oxide nanoparticles were injected intravitreally or intraveinously in albino Sprague-Dawley rats three weeks before exposing them to light damage of 1000 lux for 24 h. Electroretinographic recordings were performed a week after light damage. The progression of retinal degeneration was evaluated by measuring outer nuclear layer thickness and TUNEL staining to quantify photoreceptors death. Immunohistochemical analysis was used to evaluate retinal stress, neuroinflammatory cytokines and microglial activation. Only intravitreally injected ceria nanoparticles were detected at the level of photoreceptor outer segments 3 weeks after the light damage and electoretinographic recordings showed that ceria nanoparticles maintained visual response. Moreover, this treatment reduced neuronal death and “hot spot” extension preserving the outer nuclear layer morphology. It is noteworthy that in this work we demonstrated, for the first time, the ability of ceria nanoparticles to reduce microglial activation and their migration toward outer nuclear layer. All these evidences support ceria nanoparticles as a powerful therapeutic agent in retinal neurodegenerative processes. PMID:26469804

  18. Cerium Oxide Nanoparticles Reduce Microglial Activation and Neurodegenerative Events in Light Damaged Retina.

    PubMed

    Fiorani, Lavinia; Passacantando, Maurizio; Santucci, Sandro; Di Marco, Stefano; Bisti, Silvia; Maccarone, Rita

    2015-01-01

    The first target of any therapy for retinal neurodegeneration is to slow down the progression of the disease and to maintain visual function. Cerium oxide or ceria nanoparticles reduce oxidative stress, which is known to play a pivotal role in neurodegeneration. Our aim was to investigate whether cerium oxide nanoparticles were able to mitigate neurodegeneration including microglial activation and related inflammatory processes induced by exposure to high intensity light. Cerium oxide nanoparticles were injected intravitreally or intraveinously in albino Sprague-Dawley rats three weeks before exposing them to light damage of 1000 lux for 24 h. Electroretinographic recordings were performed a week after light damage. The progression of retinal degeneration was evaluated by measuring outer nuclear layer thickness and TUNEL staining to quantify photoreceptors death. Immunohistochemical analysis was used to evaluate retinal stress, neuroinflammatory cytokines and microglial activation. Only intravitreally injected ceria nanoparticles were detected at the level of photoreceptor outer segments 3 weeks after the light damage and electoretinographic recordings showed that ceria nanoparticles maintained visual response. Moreover, this treatment reduced neuronal death and "hot spot" extension preserving the outer nuclear layer morphology. It is noteworthy that in this work we demonstrated, for the first time, the ability of ceria nanoparticles to reduce microglial activation and their migration toward outer nuclear layer. All these evidences support ceria nanoparticles as a powerful therapeutic agent in retinal neurodegenerative processes.

  19. Enzyme:nanoparticle bioconjugates with two sequential enzymes: stoichiometry and activity of malate dehydrogenase and citrate synthase on Au nanoparticles.

    PubMed

    Keighron, Jacqueline D; Keating, Christine D

    2010-12-21

    We report the synthesis and characterization of bioconjugates in which the enzymes malate dehydrogenase (MDH) and/or citrate synthase (CS) were adsorbed to 30 nm diameter Au nanoparticles. Enzyme:Au stoichiometry and kinetic parameters (specific activity, k(cat), K(M), and activity per particle) were determined for MDH:Au, CS:Au, and three types of dual-activity MDH/CS:Au bioconjugates. For single-activity bioconjugates (MDH:Au and CS:Au), the number of enzyme molecules adsorbed per particle was dependent upon the enzyme concentration in solution, with multilayers forming at high enzyme:Au solution ratios. The specific activity of adsorbed enzyme increased with increasing number adsorbed per particle for CS:Au, but was less sensitive to stoichiometry for MDH:Au. Dual activity bioconjugates were prepared in three ways: (1) by adsorption of MDH followed by CS, (2) by adsorption of CS followed by MDH, and (3) by coadsorption of both enzymes from the same solution. The resulting bioconjugates differed substantially in the number of enzyme molecules adsorbed per particle, the specific activity of the adsorbed enzymes, and also the enzymatic activity per particle. Bioconjugates formed by adding CS to the Au nanoparticles before MDH was added exhibited higher specific activities for both enzymes than those formed by adding the enzymes in the reverse order. These bioconjugates also had 3-fold higher per-particle sequential activity for conversion of malate to citrate, despite substantially fewer copies of both enzymes present.

  20. Anti-cancer activity of bromelain nanoparticles by oral administration.

    PubMed

    Bhatnagar, Priyanka; Patnaik, Soma; Srivastava, Amit K; Mudiam, Mohan K R; Shukla, Yogeshwer; Panda, Amulya K; Pant, Aditya B; Kumar, Pradeep; Gupta, Kailash C

    2014-12-01

    Oral administration of anti-cancer drugs is an effective alternative to improve their efficacy and reduce undesired toxicity. Bromelain (BL) is known as an effective anti-cancer phyto-therapeutic agent, however, its activity is reduced upon oral administration. In addressing the issue, BL was encapsulated in Poly(lactic-co-glycolic acid) (PLGA) to formulate nanoparticles (NPs). Further, the NPs were coated with Eudragit L30D polymer to introduce stability against the gastric acidic conditions. The resultant coated NPs were characterized for BL entrapment, proteolytic activity and mean particle size. The stability and release pattern of NPs were evaluated under simulated gastrointestinal tract (GIT) pH conditions. Cytotoxicity studies carried out in human cell lines of diverse origin have shown significant dose advantage (-7-10 folds) with NPs in reducing the IC50 values compared with free BL. The cellular uptake of NPs in MCF-7, HeLa and Caco-2 cells monolayer was significantly enhanced several folds as compared to free BL. Altered expression of marker proteins associated with apoptosis and cell death (P53, P21, Bcl2, Bax) also confirmed the enhanced anti-carcinogenic potential of formulated NPs. Oral administration of NPs reduced the tumor burden of Ehrlich ascites carcinoma (EAC) in Swiss albino mice and also increased their life-span (160.0 ± 5.8%) when compared with free BL (24 ± 3.2%). The generation of reactive oxygen species, induction of apoptosis and impaired mitochondrial membrane potential in EAC cells treated with NPs confirmed the suitability of Eudragit coated BL-NPs as a promising candidate for oral chemotherapy.

  1. Antibacterial Activity of Dental Composites Containing Zinc Oxide Nanoparticles

    PubMed Central

    Sevinç, Berdan Aydin; Hanley, Luke

    2010-01-01

    The resin-based dental composites commonly used in restorations result in more plaque accumulation than other materials. Bacterial biofilm growth contributes to secondary caries and failure of resin-based dental composites. Methods to inhibit biofilm growth on dental composites have been sought for several decades. It is demonstrated here that zinc oxide nanoparticles (ZnO-NPs) blended at 10% (w/w) fraction into dental composites display antimicrobial activity and reduce growth of bacterial biofilms by roughly 80% for a single-species model dental biofilm. Antibacterial effectiveness of ZnO-NPs was assessed against Streptococcus sobrinus ATCC 27352 grown both planktonically and as biofilms on composites. Direct contact inhibition was observed by scanning electron microscopy and confocal laser scanning microscopy while biofilm formation was quantified by viable counts. An 80% reduction in bacterial counts was observed with 10% ZnO-NP-containing composites compared with their unmodified counterpart, indicating a statistically significant suppression of biofilm growth. Although, 20% of the bacterial population survived and could form a biofilm layer again, 10% ZnO-NP-containing composites maintained at least some inhibitory activity even after the third generation of biofilm growth. Microscopy demonstrated continuous biofilm formation for unmodified composites after one day growth, but only sparsely distributed biofilms formed on 10% ZnO-NP-containing composites. The minimum inhibitory concentration of ZnO-NPs suspended in S. sobrinus planktonic culture was 50 μg/ml. 10% ZnO-NP-containing composites qualitatively showed less biofilm after one day anaerobic growth of a three-species initial colonizer biofilm after when compared to unmodified composites, but did not significantly reduce growth after three days. PMID:20225252

  2. Environment-mediated structure, surface redox activity and reactivity of ceria nanoparticles

    NASA Astrophysics Data System (ADS)

    Sayle, Thi X. T.; Molinari, Marco; Das, Soumen; Bhatta, Umananda M.; Möbus, Günter; Parker, Stephen C.; Seal, Sudipta; Sayle, Dean C.

    2013-06-01

    Nanomaterials, with potential application as bio-medicinal agents, exploit the chemical properties of a solid, with the ability to be transported (like a molecule) to a variety of bodily compartments. However, the chemical environment can change significantly the structure and hence properties of a nanomaterial. Accordingly, its surface reactivity is critically dependent upon the nature of the (biological) environment in which it resides. Here, we use Molecular Dynamics (MD) simulation, Density Functional Theory (DFT) and aberration corrected TEM to predict and rationalise differences in structure and hence surface reactivity of ceria nanoparticles in different environments. In particular we calculate reactivity `fingerprints' for unreduced and reduced ceria nanoparticles immersed in water and in vacuum. Our simulations predict higher activities of ceria nanoparticles, towards oxygen release, when immersed in water because the water quenches the coordinative unsaturation of surface ions. Conversely, in vacuum, surface ions relax into the body of the nanoparticle to relieve coordinative unsaturation, which increases the energy barriers associated with oxygen release. Our simulations also reveal that reduced ceria nanoparticles are more active towards surface oxygen release compared to unreduced nanoceria. In parallel, experiment is used to explore the activities of ceria nanoparticles that have suffered a change in environment. In particular, we compare the ability of ceria nanoparticles, in an aqueous environment, to scavenge superoxide radicals compared to the same batch of nanoparticles, which have first been dried and then rehydrated. The latter show a distinct reduction in activity, which we correlate to a change in the redox chemistry associated with moving between different environments. The reactivity of ceria nanoparticles is therefore not only environment dependent, but is also influenced by the transport pathway or history required to reach the particular

  3. Environment-mediated structure, surface redox activity and reactivity of ceria nanoparticles.

    PubMed

    Sayle, Thi X T; Molinari, Marco; Das, Soumen; Bhatta, Umananda M; Möbus, Günter; Parker, Stephen C; Seal, Sudipta; Sayle, Dean C

    2013-07-07

    Nanomaterials, with potential application as bio-medicinal agents, exploit the chemical properties of a solid, with the ability to be transported (like a molecule) to a variety of bodily compartments. However, the chemical environment can change significantly the structure and hence properties of a nanomaterial. Accordingly, its surface reactivity is critically dependent upon the nature of the (biological) environment in which it resides. Here, we use Molecular Dynamics (MD) simulation, Density Functional Theory (DFT) and aberration corrected TEM to predict and rationalise differences in structure and hence surface reactivity of ceria nanoparticles in different environments. In particular we calculate reactivity 'fingerprints' for unreduced and reduced ceria nanoparticles immersed in water and in vacuum. Our simulations predict higher activities of ceria nanoparticles, towards oxygen release, when immersed in water because the water quenches the coordinative unsaturation of surface ions. Conversely, in vacuum, surface ions relax into the body of the nanoparticle to relieve coordinative unsaturation, which increases the energy barriers associated with oxygen release. Our simulations also reveal that reduced ceria nanoparticles are more active towards surface oxygen release compared to unreduced nanoceria. In parallel, experiment is used to explore the activities of ceria nanoparticles that have suffered a change in environment. In particular, we compare the ability of ceria nanoparticles, in an aqueous environment, to scavenge superoxide radicals compared to the same batch of nanoparticles, which have first been dried and then rehydrated. The latter show a distinct reduction in activity, which we correlate to a change in the redox chemistry associated with moving between different environments. The reactivity of ceria nanoparticles is therefore not only environment dependent, but is also influenced by the transport pathway or history required to reach the particular

  4. Tuning the anticancer activity of a novel pro-apoptotic peptide using gold nanoparticle platforms

    NASA Astrophysics Data System (ADS)

    Akrami, Mohammad; Balalaie, Saeed; Hosseinkhani, Saman; Alipour, Mohsen; Salehi, Fahimeh; Bahador, Abbas; Haririan, Ismaeil

    2016-08-01

    Pro-apoptotic peptides induce intrinsic apoptosis pathway in cancer cells. However, poor cellular penetration of the peptides is often associated with limited therapeutic efficacy. In this report, a series of peptide-gold nanoparticle platforms were developed to evaluate the anticancer activity of a novel alpha-lipoic acid-peptide conjugate, LA-WKRAKLAK, with respect to size and shape of nanoparticles. Gold nanoparticles (AuNPs) were found to enhance cell internalization as well as anticancer activity of the peptide conjugates. The smaller nanospheres showed a higher cytotoxicity, morphological change and cellular uptake compared to larger nanospheres and nanorods, whereas nanorods showed more hemolytic activity compared to nanospheres. The findings suggested that the anticancer and biological effects of the peptides induced by intrinsic apoptotic pathway were tuned by peptide-functionalized gold nanoparticles (P-AuNPs) as a function of their size and shape.

  5. Chemiluminescence lateral flow immunoassay based on Pt nanoparticle with peroxidase activity.

    PubMed

    Park, Jong-Min; Jung, Ha-Wook; Chang, Young Wook; Kim, Hyung-Seok; Kang, Min-Jung; Pyun, Jae-Chul

    2015-01-01

    A lateral flow immunoassay (LF-immunoassay) with an enhanced sensitivity and thermostability was developed by using Pt nanoparticles with a peroxidase activity. The Pt nanoparticles were synthesized by citrate reduction method, and the peroxidase activity of Pt nanoparticles was optimized by adjusting reaction conditions. The peroxidase activity was estimated by using Michaelis-Menten kinetics model with TMB as a chromogenic substrate. The kinetics parameters of KM and Vmax were calculated and compared with horseradish peroxidase (HRP). The thermal stability of the Pt nanoparticles was compared with horseradish peroxidase (HRP) according to the storage temperature and long-term storage period. The feasibility of lateral flow immunoassay with a chemiluminescent signal band was demonstrated by the detection of human chorionic gonadotropin (hCG) as a model analyte, and the sensitivity was determined to be improved by as much as 1000-fold compared to the conventional rapid test based on colored gold-colloids.

  6. Tuning the anticancer activity of a novel pro-apoptotic peptide using gold nanoparticle platforms

    PubMed Central

    Akrami, Mohammad; Balalaie, Saeed; Hosseinkhani, Saman; Alipour, Mohsen; Salehi, Fahimeh; Bahador, Abbas; Haririan, Ismaeil

    2016-01-01

    Pro-apoptotic peptides induce intrinsic apoptosis pathway in cancer cells. However, poor cellular penetration of the peptides is often associated with limited therapeutic efficacy. In this report, a series of peptide-gold nanoparticle platforms were developed to evaluate the anticancer activity of a novel alpha-lipoic acid-peptide conjugate, LA-WKRAKLAK, with respect to size and shape of nanoparticles. Gold nanoparticles (AuNPs) were found to enhance cell internalization as well as anticancer activity of the peptide conjugates. The smaller nanospheres showed a higher cytotoxicity, morphological change and cellular uptake compared to larger nanospheres and nanorods, whereas nanorods showed more hemolytic activity compared to nanospheres. The findings suggested that the anticancer and biological effects of the peptides induced by intrinsic apoptotic pathway were tuned by peptide-functionalized gold nanoparticles (P-AuNPs) as a function of their size and shape. PMID:27491007

  7. Photocatalytic activity of biogenic silver nanoparticles synthesized using potato (Solanum tuberosum) infusion.

    PubMed

    Roy, Kaushik; Sarkar, C K; Ghosh, C K

    2015-07-05

    In this study, we have reported a fast and eco-benign procedure to synthesis silver nanoparticle at room temperature using potato (Solanum tuberosum) infusion along with the study of its photocatalytic activity on methyl orange dye. After addition of potato infusion to silver nitrate solution, the color of the mixture changed indicating formation of silver nanoparticles. Time dependent UV-Vis spectra were obtained to study the rate of nanoparticle formation with time. Purity and crystallinity of the biogenic silver nanoparticles were examined by X-ray diffraction (XRD). Average size and morphology of the nanoparticles were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Fourier transform infra-red spectroscopy (FTIR) was employed to detect functional bio-molecules responsible that contribute to the reduction and capping of biosynthesized Ag nanoparticles. Further, these synthesized nanoparticles were used to investigate their ability to degrade methyl orange dye under sunlight irradiation and the results showed effective photocatalytic property of these biogenic silver nanoparticles.

  8. Photocatalytic activity of biogenic silver nanoparticles synthesized using potato (Solanum tuberosum) infusion

    NASA Astrophysics Data System (ADS)

    Roy, Kaushik; Sarkar, C. K.; Ghosh, C. K.

    2015-07-01

    In this study, we have reported a fast and eco-benign procedure to synthesis silver nanoparticle at room temperature using potato (Solanum tuberosum) infusion along with the study of its photocatalytic activity on methyl orange dye. After addition of potato infusion to silver nitrate solution, the color of the mixture changed indicating formation of silver nanoparticles. Time dependent UV-Vis spectra were obtained to study the rate of nanoparticle formation with time. Purity and crystallinity of the biogenic silver nanoparticles were examined by X-ray diffraction (XRD). Average size and morphology of the nanoparticles were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Fourier transform infra-red spectroscopy (FTIR) was employed to detect functional bio-molecules responsible that contribute to the reduction and capping of biosynthesized Ag nanoparticles. Further, these synthesized nanoparticles were used to investigate their ability to degrade methyl orange dye under sunlight irradiation and the results showed effective photocatalytic property of these biogenic silver nanoparticles.

  9. Electrocatalytic activities of alkyne-functionalized copper nanoparticles in oxygen reduction in alkaline media

    NASA Astrophysics Data System (ADS)

    Liu, Ke; Song, Yang; Chen, Shaowei

    2014-12-01

    Stable alkyne-capped copper nanoparticles were prepared by chemical reduction of copper acetate with sodium borohydride in the presence of alkyne ligands. Transmission electron microscopic measurements showed that nanoparticles were well dispersed with a diameter in the range of 4-6 nm. FTIR and photoluminescence spectroscopic measurements confirmed the successful attachment of the alkyne ligands onto the nanoparticle surface most likely forming Cu-Ctbnd interfacial bonds. XPS measurements indicated the formation of a small amount of CuO in the nanoparticles with a satellite peak where the binding energy red-shifted with increasing Cu(II) concentration. Cu2O was also detected in the nanoparticles. Similar results were observed with commercial CuO nanoparticles. Electrochemical studies showed that the as-prepared alkyne-capped copper nanoparticles exhibited apparent electrocatalytic activity in oxygen reduction in alkaline media, a performance that was markedly better than those reported earlier with poly- or single-crystalline copper electrodes; and the fraction of peroxides in the final products decreased with decreasing concentration of oxide components in the nanoparticles.

  10. Facile synthesis of ferromagnetic Ni doped CeO2 nanoparticles with enhanced anticancer activity

    NASA Astrophysics Data System (ADS)

    Abbas, Fazal; Jan, Tariq; Iqbal, Javed; Ahmad, Ishaq; Naqvi, M. Sajjad H.; Malik, Maaza

    2015-12-01

    NixCe1-xO2 (where x = 0, 0.01, 0.03, 0.05 and 0.07) nanoparticles were synthesized by soft chemical method and were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, UV-vis absorption spectroscopy and vibrating sample magnetometer (VSM). XRD and Raman results indicated the formation of single phase cubic fluorite structure for the synthesized nanoparticles. Ni dopant induced excessive structural changes such as decrease in crystallite size as well as lattice constants and enhancement in oxygen vacancies in CeO2 crystal structure. These structural variations significantly influenced the optical and magnetic properties of CeO2 nanoparticles. The synthesized NixCe1-xO2 nanoparticles exhibited room temperature ferromagnetic behavior. Ni doping induced effects on the cytotoxicity of CeO2 nanoparticles were examined against HEK-293 healthy cell line and SH-SY5Y neuroblastoma cancer cell line. The prepared NixCe1-xO2 nanoparticles demonstrated differential cytotoxicity. Furthermore, anticancer activity of CeO2 nanoparticles observed to be significantly enhanced with Ni doping which was found to be strongly correlated with the level of reactive oxygen species (ROS) production. The prepared ferromagnetic NixCe1-xO2 nanoparticles with differential cytotoxic nature may be potential for future targeted cancer therapy.

  11. Anti-metastatic activity of biologically synthesized gold nanoparticles on human fibrosarcoma cell line HT-1080.

    PubMed

    Karuppaiya, Palaniyandi; Satheeshkumar, Elumalai; Chao, Wei-Ting; Kao, Lin-Yi; Chen, Emily Chin-Fun; Tsay, Hsin-Sheng

    2013-10-01

    Plants are exploited as a potential source for the large-scale production of noble gold nanoparticles in the recent years owing to their various potential applications in nanobiotechnology and nanomedicine. The present work describes green biosynthetic procedures for the production of gold nanoparticles for the first time by using an aqueous extract of the Dysosma pleiantha rhizome. The biosynthesized gold nanoparticles were confirmed and characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy equipped with energy dispersive spectroscopy. The results revealed that aqueous extract of D. pleiantha rhizome has potential to reduce chloroauric ions into gold nanoparticles and the synthesized gold nanoparticles were showed spherical in shape with an average of 127nm. Further, we investigated the anti-metastatic activity of biosynthesized gold nanoparticles against human fibrosarcoma cancer cell line HT-1080. The results showed that the biosynthesized gold nanoparticles were non-toxic to cell proliferation and, also it can inhibit the chemo-attractant cell migration of human fibrosarcoma cancer cell line HT-1080 by interfering the actin polymerization pathway. Thus, the usage of gold nanoparticles biosynthesized from D. pleiantha rhizome can be used as a potential candidate in the drug and gene delivery to metastatic cancer.

  12. Size controlled synthesis of biocompatible gold nanoparticles and their activity in the oxidation of NADH.

    PubMed

    Chandran, Parvathy R; Naseer, M; Udupa, N; Sandhyarani, N

    2012-01-13

    Size and shape controlled synthesis remains a major bottleneck in the research on nanoparticles even after the development of different methods for their preparation. By tuning the size and shape of a nanoparticle, the intrinsic properties of the nanoparticle can be controlled leading tremendous potential applications in different fields of science and technology. We describe a facile route for the one pot synthesis of gold nanoparticles in water using monosodium glutamate as the reducing and stabilizing agent in the absence of seed particles. The particle diameter can be easily controlled by varying the pH of the reaction medium. Nanoparticles were characterized using scanning electron microscopy, UV-vis absorption spectroscopy, cyclic voltammetry, and dynamic light scattering. Zeta potential measurements were made to compare the stability of the different nanoparticles. The results suggest that lower pH favours a nucleation rate giving rise to smaller particles and higher pH favours a growth rate leading to the formation of larger particles. The synthesized nanoparticles are found to be stable and biocompatible. The nanoparticles synthesized at high pH exhibited a good electrocatalytic activity towards oxidation of nicotinamide adenine dinucleotide (NADH).

  13. Photochemical air pollution. Part I

    SciTech Connect

    Goldstein E.; Hackney, J.D.; Rokaw, S.N.

    1985-03-01

    In this paper, epidemiologic studies are reported which indicate that high photochemical oxidant exposures: do not cause mortality or serious illness; may increase the risk of asthmatic attacks in a small percentage of asthmatic patients; appear to reduce pulmonary function in smokers and nonsmokers after long-term exposure; cause acute discomfort of eye and throat, chest irritation and cough; and interfere with athletic performance. Exposure to high ambient levels of NO/sub 2/ is not associated with mortality, serious disease or respiratory dysfunction, but self-limiting symptoms of respiratory irritation or illness may develop in children. 106 references, 2 figures, 1 table.

  14. Mechanistic Study of Silver Nanoparticle's Synthesis by Dragon's Blood Resin Ethanol Extract and Antiradiation Activity.

    PubMed

    Hasan, Murtaza; Iqbal, Javed; Awan, Umer; Saeed, Yasmeen; Ranran, Yuan; Liang, Yanli; Dai, Rongji; Deng, Yulin

    2015-02-01

    Biological synthesis of nanoparticles is best way to avoid exposure of hazardous materials as compared to chemical manufacturing process which is a severe threat not only to biodiversity but also to environment. In present study, we reported a novel method of finding antiradiation compounds by bioreducing mechanism of silver nanoparticles formation using 50% ethanol extract of Dragons blood, a famous Chinese herbal plant. Color change during silver nanoparticles synthesis was observed and it was confirmed by ultra violet (UV) visible spectroscopy at wave length at 430 nm after 30 min of reaction at 60 °C. Well dispersed round shaped silver nanoparticles with approximate size (4 nm to 50 nm) were measured by TEM and particle size analyser. Capping of biomolecules on Ag nanoparticles was characterized by FTIR spectra. HPLC analysis was carried out to find active compounds in the extract. Furthermore, antiradiation activity of this extract was tested by MTT assay in vitro after incubating the SH-SY5Y cells for 24 h at 37 °C. The results indicate that presence of active compounds in plant extract not only involves in bioreduction process but also shows response against radiation. The dual role of plant extract as green synthesis of nanoparticles and exhibit activity against radiation which gives a new way of fishing out active compounds from complex herbal plants.

  15. Synthesis and thermal transport studies of nanofluids based on metal decorated photochemically oxidized multiwalled carbon nanotubes.

    PubMed

    Aravind, S S Jyothirmayee; Ramaprabhu, S

    2012-08-01

    Nanoparticle fluid suspensions were prepared using photochemically functionalized multiwalled carbon nanotubes in polar base fluids. Multiwalled carbon nanotubes prepared by catalytic chemical vapour deposition technique have been functionalized by irradiating with ultraviolet light of wavelength 254 nm. The photochemical oxidation of multiwalled carbon nanotubes under UV irradiation introduces oxygen containing functional groups onto the surface of the nanotubes, generating new defects on their structure. Silver nanoparticles have been deposited over multiwalled carbon nanotubes by chemical method. The enhancement in thermal conductivity of the prepared nanofluids using functionalized multiwalled carbon nanotubes and Ag nanoparticles deposited functionalized multiwalled carbon nanotubes with volume fraction, temperature and aspect ratio has been demonstrated. Silver deposited functionalized multiwalled carbon nanotubes based nanofluids in DI water with 0.02% volume fraction exhibit a thermal conductivity enhancement of 9.9% and 47% at room temperature and at 50 degrees C respectively.

  16. Syntheses of amorphous and crystalline cupric sulfide nanoparticles and study on the specific activities on different cells.

    PubMed

    Guo, Yuming; Zhang, Jie; Yang, Lin; Wang, Huajie; Wang, Feifei; Zheng, Zhi

    2010-05-28

    Copper sulfide amorphous nanoparticles and nanocrystals were prepared successfully by a special process. These CuS nanoparticles could specifically and significantly induce the apoptosis and inhibit the proliferation of human cancer cells rather than normal cells. Moreover, the biological activities of these nanoparticles are related to their polymorphs.

  17. Photochemical mutagenesis: examples and toxicological relevance.

    PubMed

    Gocke, E

    2001-01-01

    Induction of DNA damage as a consequence of exposure to UV light has been established as the major cause of skin cancer. DNA molecules absorb photon energy directly for wavelengths <320 nm, and lead to well-characterized mutagenic DNA damage. Alternatively, endogenous or exogenous chemicals (sensitizers) may absorb light with the potential of subsequent energy or electron transfer, and lead indirectly to DNA damage. A few light-absorbing pharmaceuticals have long been known to cause photo(geno)toxic effects. Notably, psoralen and chlorpromazine derivatives have been established as photomutagens and the reaction mechanisms have been identified; the fluoroquinolone antibiotics have more recently been recognized as being photomutagenic. The type of DNA damage and the modulation by antioxidants indicate the involvement of reactive oxygen species (ROS), but other mechanisms are also reported for, at least, some derivatives. In routine genotoxicity studies, we observed the photomutagenic activity of a compound (Ro 19-8022) under development as an anxiolytic agent in the Ames tester strain TA102 under normal laboratory illumination conditions. Further investigations showed strong photogenotoxic activity in tests for gene mutations and chromosomal aberrations in mammalian cells. The finding led to the termination of drug development. Another example of a pharmaceutical for which photogenotoxic properties were observed during development is Ro 47-7737, a bisquinoline derivative of the antimalaria compound chloroquine. Also in this case, the photochemical reactivity contributed to the termination of the development process. The risk/benefit assessment for the described compounds has to take into account the human exposure situation, for example, the ability to avoid light exposure during treatment. Consideration of photochemical mutagenesis is specifically important for sunscreen ingredients. The active components of sunscreen lotions are efficient UV absorbers. Consequently

  18. Antibacterial activity of silver and zinc nanoparticles against Vibrio cholerae and enterotoxic Escherichia coli.

    PubMed

    Salem, Wesam; Leitner, Deborah R; Zingl, Franz G; Schratter, Gebhart; Prassl, Ruth; Goessler, Walter; Reidl, Joachim; Schild, Stefan

    2015-01-01

    Vibrio cholerae and enterotoxic Escherichia coli (ETEC) remain two dominant bacterial causes of severe secretory diarrhea and still a significant cause of death, especially in developing countries. In order to investigate new effective and inexpensive therapeutic approaches, we analyzed nanoparticles synthesized by a green approach using corresponding salt (silver or zinc nitrate) with aqueous extract of Caltropis procera fruit or leaves. We characterized the quantity and quality of nanoparticles by UV-visible wavelength scans and nanoparticle tracking analysis. Nanoparticles could be synthesized in reproducible yields of approximately 10(8) particles/ml with mode particles sizes of approx. 90-100 nm. Antibacterial activity against two pathogens was assessed by minimal inhibitory concentration assays and survival curves. Both pathogens exhibited similar resistance profiles with minimal inhibitory concentrations ranging between 5×10(5) and 10(7) particles/ml. Interestingly, zinc nanoparticles showed a slightly higher efficacy, but sublethal concentrations caused adverse effects and resulted in increased biofilm formation of V. cholerae. Using the expression levels of the outer membrane porin OmpT as an indicator for cAMP levels, our results suggest that zinc nanoparticles inhibit adenylyl cyclase activity. This consequently deceases the levels of this second messenger, which is a known inhibitor of biofilm formation. Finally, we demonstrated that a single oral administration of silver nanoparticles to infant mice colonized with V. cholerae or ETEC significantly reduces the colonization rates of the pathogens by 75- or 100-fold, respectively.

  19. Antibacterial activity of silver and zinc nanoparticles against Vibrio cholerae and enterotoxic Escherichia coli

    PubMed Central

    Salem, Wesam; Leitner, Deborah R.; Zingl, Franz G.; Schratter, Gebhart; Prassl, Ruth; Goessler, Walter; Reidl, Joachim; Schild, Stefan

    2015-01-01

    Vibrio cholerae and enterotoxic Escherichia coli (ETEC) remain two dominant bacterial causes of severe secretory diarrhea and still a significant cause of death, especially in developing countries. In order to investigate new effective and inexpensive therapeutic approaches, we analyzed nanoparticles synthesized by a green approach using corresponding salt (silver or zinc nitrate) with aqueous extract of Caltropis procera fruit or leaves. We characterized the quantity and quality of nanoparticles by UV–visible wavelength scans and nanoparticle tracking analysis. Nanoparticles could be synthesized in reproducible yields of approximately 108 particles/ml with mode particles sizes of approx. 90–100 nm. Antibacterial activity against two pathogens was assessed by minimal inhibitory concentration assays and survival curves. Both pathogens exhibited similar resistance profiles with minimal inhibitory concentrations ranging between 5 × 105 and 107 particles/ml. Interestingly, zinc nanoparticles showed a slightly higher efficacy, but sublethal concentrations caused adverse effects and resulted in increased biofilm formation of V. cholerae. Using the expression levels of the outer membrane porin OmpT as an indicator for cAMP levels, our results suggest that zinc nanoparticles inhibit adenylyl cyclase activity. This consequently deceases the levels of this second messenger, which is a known inhibitor of biofilm formation. Finally, we demonstrated that a single oral administration of silver nanoparticles to infant mice colonized with V. cholerae or ETEC significantly reduces the colonization rates of the pathogens by 75- or 100-fold, respectively. PMID:25466205

  20. Enhancement of anti-inflammatory activity of bromelain by its encapsulation in katira gum nanoparticles.

    PubMed

    Bernela, Manju; Ahuja, Munish; Thakur, Rajesh

    2016-06-05

    Bromelain-loaded katira gum nanoparticles were synthesized using 3 level optimization process and desirability approach. Nanoparticles of the optimized batch were characterized using particle size analysis, zeta potential, transmission electron microscopy and Fourier-transform infrared spectroscopy. Investigation of their in vivo anti-inflammatory activity by employing carrageenan induced rat-paw oedema method showed that encapsulation of bromelain in katira gum nanoparticles substantially enhanced its anti-inflammatory potential. This may be attributed to enhanced absorption owing to reduced particle size or to protection of bromelain from acid proteases.

  1. Biosynthesis of silver nanoparticles using citrus sinensis peel extract and its antibacterial activity

    NASA Astrophysics Data System (ADS)

    Kaviya, S.; Santhanalakshmi, J.; Viswanathan, B.; Muthumary, J.; Srinivasan, K.

    2011-08-01

    Biosynthesis of silver nanoparticles (AgNPs) was achieved by a novel, simple green chemistry procedure using citrus sinensis peel extract as a reducing and a capping agent. The effect of temperature on the synthesis of silver nanoparticles was carried out at room temperature (25 °C) and 60 °C. The successful formation of silver nanoparticles has been confirmed by UV-vis, FTIR, XRD, EDAX, FESEM and TEM analysis and their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa (Gram-negative), and Staphylococcus aureus (Gram-positive) has been studied. The results suggest that the synthesized AgNPs act as an effective antibacterial agent.

  2. Enhanced peroxidase activity and tumour tissue visualization by cobalt-doped magnetoferritin nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Tongwei; Cao, Changqian; Tang, Xu; Cai, Yao; Yang, Caiyun; Pan, Yongxin

    2017-01-01

    Magnetoferritin (M-HFn) is a biomimetic magnetic nanoparticle with a human heavy-chain ferritin (HFn) shell, trapping a magnetite (Fe3O4) core that has inherited peroxidase-like activity. In this study, cobalt-doped M-HFn nanoparticles (M-HFn-Co x Fe3-x O4) with different amounts of cobalt were successfully synthesized. Experimental results indicate that the controlled doping of a certain amount of cobalt into the magnetite cores of M-HFn nanoparticles enhances its peroxidase-like catalytic activity and efficacy for visualizing tumour tissues. For example, compared with sample Co0 (without cobalt doping), the peroxidase-like activity of the cobalt-doped nanoparticle sample Co60 (with a cobalt doping molar percentage of ˜34.2%) increases 1.7 times, and has the maximal reaction velocity (V max) values. Moreover, after a one-step incubation with Co60 nanoparticles, and using the peroxidase substrate 3,3‧-diaminobenzidine tetrahydrochloride (DAB) for colour development, the tumour tissues of breast, colorectal, stomach and pancreas tumours showed a deeper brown colour with clear boundaries between the healthy and tumourous cells. Therefore, this suggests that the cobalt-doped magnetoferritin nanoparticles enhance peroxidase activity and tumour tissue visualization.

  3. Antimicrobial activity of metal based nanoparticles against microbes associated with diseases in aquaculture.

    PubMed

    Swain, P; Nayak, S K; Sasmal, A; Behera, T; Barik, S K; Swain, S K; Mishra, S S; Sen, A K; Das, J K; Jayasankar, P

    2014-09-01

    The emergence of diseases and mortalities in aquaculture and development of antibiotics resistance in aquatic microbes, has renewed a great interest towards alternative methods of prevention and control of diseases. Nanoparticles have enormous potential in controlling human and animal pathogens and have scope of application in aquaculture. The present investigation was carried out to find out suitable nanoparticles having antimicrobial effect against aquatic microbes. Different commercial as well as laboratory synthesized metal and metal oxide nanoparticles were screened for their antimicrobial activities against a wide range of bacterial and fungal agents including certain freshwater cyanobacteria. Among different nanoparticles, synthesized copper oxide (CuO), zinc oxide (ZnO), silver (Ag) and silver doped titanium dioxide (Ag-TiO2) showed broad spectrum antibacterial activity. On the contrary, nanoparticles like Zn and ZnO showed antifungal activity against fungi like Penicillium and Mucor species. Since CuO, ZnO and Ag nanoparticles showed higher antimicrobial activity, they may be explored for aquaculture use.

  4. Artemisia capillaris extracts as a green factory for the synthesis of silver nanoparticles with antibacterial activities.

    PubMed

    Park, Youmie; Noh, Hwa Jung; Han, Lina; Kim, Hyun-Seok; Kim, Yong-Jae; Choi, Jae Sue; Kim, Chong-Kook; Kim, Yeong Shik; Cho, Seonho

    2012-09-01

    We report a green synthesis of silver nanoparticles that uses extracts from the aerial part of Artemisia capillaris. Both water and 70% ethanol extracts successfully generated silver nanoparticles. The formation of silver nanoparticles was confirmed by surface plasmon resonance bands, Fourier transform-infrared spectra, high resolution-transmission electron and atomic force microscopic images. Various shapes of silver nanoparticles were generated with an average diameter of 29.71 nm with water extract and 29.62 nm with 70% ethanol extract. An improvement in antibacterial activity (MIC 8.35-16.7 microg/mL) was observed against a total of twenty different strains of Gram-negative and Gram-positive bacteria. A remarkable enhancement (approximately 12-fold) was observed against Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, Klebsiella oxytoca, and Klebsiella areogenes when compared with the extract alone. Silver nanoparticles produced by the 70% ethanol extract showed slightly higher antibacterial activity than those generated with the water extract. The correlation between total flavonoid content of each extract and the antibacterial activity did not exert any significant relationships. This report suggests that plant extracts have the potential to be used as powerful reducing agents for the production of biocompatible silver nanoparticles possessing enhanced antibacterial activities.

  5. Photochemical behaviour of phenylurea herbicides.

    PubMed

    Amine-Khodja, Amina; Boulkamh, Abdelaziz; Boule, Pierre

    2004-02-01

    The photochemical behaviour of phenylurea herbicides in aqueous solution is highly dependent on the nature and position of substituents on the ring. Most of these herbicides are methylated on the urea moiety, the other substituents are usually halogens or methoxy groups. The main reaction involving the aromatic ring of unhalogenated phenylureas excited at wavelengths shorter than 300 nm is an intramolecular rearrangement, similar to photo-Fries rearrangement, whereas with halogenated derivatives, photohydrolysis is the main transformation pathway. In the particular case of para-halogenated phenylureas, the intermediate formation of a carbene is observed. When the urea moiety is substituted with a methoxyl group, demethoxylation is a competitive reaction. N-Demethylation or oxidation of methyl groups is also observed, but with a lower yield. Photooxidation of phenylureas can also be induced by photocatalysis, iron salts or humic substances. In the absence of water, the main route for phototransformation of diuron is the oxidation or elimination of methyl groups. It is entirely possible that a photochemical intermediate could turn out to be more toxic than the initial herbicide.

  6. Enhanced anti-cancer and antimicrobial activities of curcumin nanoparticles.

    PubMed

    Adahoun, Mo'ath Ahmad; Al-Akhras, Mohammed-Ali Hassan; Jaafar, Mohamad Suhaimi; Bououdina, Mohamed

    2017-02-01

    Background Curcumin (diferuloylmethane) is a polyphenol derived from the plant Curcuma longa, commonly called turmeric. Extensive research over the last 50 years has demonstrated that these polyphenols play an important role in the maintenance of health and prevention of diseases, in addition to its therapeutic benefits such as anti-tumor, anti-inflammatory, and anti-oxidant activities. Materials and methods This study is devoted to the enhancement of the solubility and bioavailability of curcumin nanoparticles prepared by a process based on a wet-milling technique and then examine in vitro against prostate cancer cell line 3 (PC3), human embryonic kidney cell line (HEK), human erythrocytes (red blood cells (RBCs)), and against fourth different bacterial strains two gram-positive (Micrococcus luteus ATCC 9341, Staphylococcus aureus ATCC 29213), two gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853). Results The cell viability curve, the half maximal inhibitory concentration (IC50), and the minimum bactericidal concentration (MBC) were evaluated. Nanocurcumin displayed significant activity against cancer cell line (PC3) and low toxicity against normal cells (HEK) compared with parent curcumin in favor of PC3 (P < 0.05). In addition, it was found that the efficiency of toxicity for nanocurcumin against PC3 (E% = 59.66%) was much better than HEK (E% = 36.07%) compared with parent curcumin. The results also demonstrate that, although nanocurcumin has a little more ability to lays RBCs than parent curcumin after incubated 60 min, but the hemolysis % remained very low and there was no significant difference between hemolysis % of nanocurcumin and parent curcumin (P > 0.05). On the other hand, the results demonstrate that, the MBCs of nanocurcumin were lower than curcumin for all different bacterial strains. Moreover, the selected gram-positive bacteria had higher sensitivity than the selected gram-negative bacteria for both

  7. Formation of gold decorated porphyrin nanoparticles and evaluation of their photothermal and photodynamic activity.

    PubMed

    Chen, Ruey-Juen; Chen, Po-Chung; Prasannan, Adhimoorthy; Vinayagam, Jayaraman; Huang, Chun-Chiang; Chou, Peng-Yi; Weng, Cheng-Chih; Tsai, Hsieh Chih; Lin, Shuian-Yin

    2016-06-01

    A core-shell gold (Au) nanoparticle with improved photosensitization have been successfully fabricated using Au nanoparticles and 5,10,15,20 tetrakis pentafluorophenyl)-21H,23H-porphine (PF6) dye, forming a dyad through molecular self-assembly. Au nanoparticles were decorated on the shell and PF6 was placed in the core of the nanoparticles. Highly stable Au nanoparticles were achieved using PF6 with poly(N-vinylcaprolactam-co-N-vinylimidazole)-g-poly(D,L-lactide) graft copolymer hybridization. This was compared with hybridization using cetyltrimethylammonium bromide and polyethylene glycol-b-poly(D,L-lactide) for shell formation with PF6-Au. The resulting PF6-poly(N-vinylcaprolactam-co-N-vinylimidazole)-g-poly(D,L-lactide)-Au core-shell nanoparticle were utilized for photothermal and photodynamic activities. The spectroscopic analysis and zeta potential values of micelles revealed the presence of a thin Au layer coated on the PF6 nanoparticle surface, which generally enhanced the thermal stability of the gold nanoparticles and the photothermal effect of the shell. The core-shell PF6-Au nanoparticles were avidly taken up by cells and demonstrated cellular phototoxicity upon irradiation with 300W halogen lamps. The structural arrangement of PF6 dyes in the core-shell particles assures the effectiveness of singlet oxygen production. The study verifies that PF6 particles when companied with Au nanoparticles as PF6-Au have possible combinational applications in photodynamic and photothermal therapies for cancer cells because of their high production of singlet oxygen and heat.

  8. Preparation of aminodextran-CdS nanoparticle complexes and biologically active antibody-aminodextran-CdS nanoparticle conjugates

    SciTech Connect

    Sondi, I.; Siiman, O.; Koester, S.; Matijevic, E.

    2000-04-04

    Stable aqueous dispersions consisting of CdS nanoparticles having modal diameters, ranging between 2 and 8 nm, were prepared with amino-derivatized polysaccharides (aminodextrans, hence abbreviated as Amdex) as the stabilizing agents. The size, stability, and luminescence intensity of such dispersions were shown to be dependent on the types of the cadmium salts and aminodextrans used, as well as on the reactant concentrations. Specifically, it was demonstrated that the degree of substitution of amino groups in the aminodextran molecules greatly affected the properties of the dispersions; i.e., with higher degree of substitution, smaller CdS particles and higher luminescence intensity were achieved. It was also shown that the Amdex-CdS nanoparticle complexes could be activated and conjugated with antibody by conventional means. Molecular weight ranges of the Amdex and their complexes with CdS nanoparticles and the purity of antibody-Amdex-CdS nanoparticle conjugates were determined by polyacrylamide gel electrophoresis combined with Coomassie blue staining of resultant gel bands. The purified conjugate of the aminodextran-CdS nanoparticle complex with anti-CD4 monoclonal antibody was mixed with a whole blood control, followed by indirect sheep antimouse antibody-phycoerythrin (SAM-PE) labeling of washed cells incubated with T4-5X-Amdex-CdS. Red blood cells were then lysed and quenched, and the resulting mixture, which was run on a flow cytometer with 488.0 nm argon ion laser excitation, suggested that the T4 antibody from the conjugate was present specifically on lymphocytes.

  9. Design of Raman active nanoparticles for SERS-based detection

    NASA Astrophysics Data System (ADS)

    Garza, Javier T.; Cote, Gerard L.

    2016-03-01

    Timely detection of cardiac biomarkers is needed to diagnose acute myocardial infarction, implement the appropriate early treatment, and significantly reduce the chance of mortality. Ideally, for maximizing patient impact, a point of care device needs to be designed that is fast, sensitive, reliable, and small enough to be used in the ambulance and emergency department. Surface enhanced Raman spectroscopy (SERS) is a sensitive optical technique that can potentially be used to quantify the cardiac biomarkers of interest. In this work, silver nanoparticles were functionalized with a Raman reporter molecule and human cardiac Troponin I (cTnI) as an essential component of binding assays. Aggregated nanoparticles with the Raman reporter molecules were encapsulated in a silica shell to form SERS hotspots. Besides having a specific Raman spectra and binding affinity to cardiac Troponin I antibodies, the nanoparticles were designed to exhibit stability by using silica and polyethylene glycol (PEG) as part of the bioconjugation strategy. The specific narrow peaks from the Raman reporter molecule SERS signal allow for potential multiplexing capabilities as different Raman reporter molecules can be used in functionalized nanoparticles with different cardiac biomarkers. The SERS spectrum of the functionalized nanoparticles was measured to assess its potential to be used in an assay.

  10. Development of active biofilms of quinoa (Chenopodium quinoa W.) starch containing gold nanoparticles and evaluation of antimicrobial activity.

    PubMed

    Pagno, Carlos H; Costa, Tania M H; de Menezes, Eliana W; Benvenutti, Edilson V; Hertz, Plinho F; Matte, Carla R; Tosati, Juliano V; Monteiro, Alcilene R; Rios, Alessandro O; Flôres, Simone H

    2015-04-15

    Active biofilms of quinoa (Chenopodium quinoa, W.) starch were prepared by incorporating gold nanoparticles stabilised by an ionic silsesquioxane that contains the 1,4-diazoniabicyclo[2.2.2]octane chloride group. The biofilms were characterised and their antimicrobial activity was evaluated against Escherichiacoli and Staphylococcusaureus. The presence of gold nanoparticles produces an improvement in the mechanical, optical and morphological properties, maintaining the thermal and barrier properties unchanged when compared to the standard biofilm. The active biofilms exhibited strong antibacterial activity against food-borne pathogens with inhibition percentages of 99% against E. coli and 98% against S. aureus. These quinoa starch biofilms containing gold nanoparticles are very promising to be used as active food packaging for the maintenance of food safety and extension of the shelf life of packaged foods.

  11. Synthesis and polymorphic control for visible light active titania nanoparticles

    NASA Astrophysics Data System (ADS)

    Kaewgun, Sujaree

    Titania (TiO2) is useful for many applications in photocatalysis, antimicrobials, pigment, deodorization, and decomposition of harmful organics and undesirable compounds in the air and waste water under UV irradiation. Among the three phases of TiO2, Rutile, Anatase, and Brookite, studies have been more focused on the anatase and rutile phases. Pure brookite is the most difficult phase to prepare, even under hydrothermal conditions. Predominantly brookite phase TiO2 nanoparticles were prepared by the Water-based Ambient Condition Sol (WACS) process in our laboratory. The objectives of this research were to enhance visible light active (VLA) photocatalytic properties of polymorphic brookite TiO2 by minimizing the lattice defects and narrowing band gap of titania by nitrogen and/or carbon chromophone, and to investigate the deactivation, reusability, and regeneration of the VLA titania in order to design better titania catalysts for organic compound degradation applications. In order to study the influence of hydroxyl content on photocatalytic activities (PCAs) of polymorphic titania nanoparticles, the WACS samples were post-treated by a Solvent-based Ambient Condition Sol (SACS) process in sec-butanol (sec-BuOH). All samples were characterized for phase composition, surface area, hydroxyl contamination, and particle morphology by x-ray diffraction, N2 physisorption, FT-IR, solid state 1H NMR and scanning electron microscopy, and then compared to a commercial titania, Degussa P25. Evaluation of methyl orange (MO) degradation under UV irradiation results showed that the lower lattice hydroxyl content in SACS titania enhanced the PCA. As-prepared titania and SACS samples, which have similar surface areas and crystallinity, were compared in order to prove that the superior PCA came from the reduction in the lattice hydroxyl content. To enhance PCA and VLA properties of WACS, an alternative high boiling point polar solvent, N-methylpyrrolidone (NMP), was utilized in the

  12. Interactions of PLGA nanoparticles with blood components: protein adsorption, coagulation, activation of the complement system and hemolysis studies.

    PubMed

    Fornaguera, Cristina; Calderó, Gabriela; Mitjans, Montserrat; Vinardell, Maria Pilar; Solans, Conxita; Vauthier, Christine

    2015-04-14

    The intravenous administration of poly(lactic-co-glycolic) acid (PLGA) nanoparticles has been widely reported as a promising alternative for delivery of drugs to specific cells. However, studies on their interaction with diverse blood components using different techniques are still lacking. Therefore, in the present work, the interaction of PLGA nanoparticles with blood components was described using different complementary techniques. The influence of different encapsulated compounds/functionalizing agents on these interactions was also reported. It is worth noting that all these techniques can be simply performed, without the need for highly sophisticated apparatus or skills. Moreover, their transference to industries and application of quality control could be easily performed. Serum albumin was adsorbed onto all types of tested nanoparticles. The saturation concentration was dependent on the nanoparticle size. In contrast, fibrinogen aggregation was dependent on nanoparticle surface charge. The complement activation was also influenced by the nanoparticle functionalization; the presence of a functionalizing agent increased complement activation, while the addition of an encapsulated compound only caused a slight increase. None of the nanoparticles influenced the coagulation cascade at low concentrations. However, at high concentrations, cationized nanoparticles did activate the coagulation cascade. Interactions of nanoparticles with erythrocytes did not reveal any hemolysis. Interactions of PLGA nanoparticles with blood proteins depended both on the nanoparticle properties and the protein studied. Independent of their loading/surface functionalization, PLGA nanoparticles did not influence the coagulation cascade and did not induce hemolysis of erythrocytes; they could be defined as safe concerning induction of embolization and cell lysis.

  13. Lectin coated MgO nanoparticle: its toxicity, antileishmanial activity, and macrophage activation.

    PubMed

    Jebali, Ali; Hekmatimoghaddam, Seyedhossein; Kazemi, Bahram; Allaveisie, Azra; Masoudi, Alireza; Daliri, Karim; Sedighi, Najme; Ranjbari, Javad

    2014-10-01

    The purpose of this research was to evaluate toxicity of uncoated magnesium oxide nanoparticles (MgO NPs), MgO NPs coated with Peanut agglutinin (PNA) lectin, and PNA alone on the promastigotes of Leishmania major (L. major) and macrophages of BALB/c mice. On the other hand, antileishmanial property of uncoated MgO NPs, lectin coated MgO NPs, and PNA lectin alone was evaluated, and also macrophage activation was investigated after treatment with these materials by measurement of nitrite, H2O2, and some interleukins. This study showed that PNA lectin and lectin coated MgO NPs had approximately no toxicity on L. major and macrophages, but some toxic effects were observed for uncoated MgO NPs, especially at concentration of 500 µg/mL. Interestingly, lectin coated MgO NPs had the highest antileishmanial activity and macrophage activation, compared with uncoated MgO NPs and PNA lectin.

  14. Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

    2015-01-01

    A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5-10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO2 nanocrystals.

  15. The nonmonotonous shift of quantum plasmon resonance and plasmon-enhanced photocatalytic activity of gold nanoparticles.

    PubMed

    Ding, Si-Jing; Yang, Da-Jie; Li, Jin-Ling; Pan, Gui-Ming; Ma, Liang; Lin, Yong-Jie; Wang, Jia-Hong; Zhou, Li; Feng, Min; Xu, Hongxing; Gao, Shiwu; Wang, Qu-Quan

    2017-03-02

    The surface plasmon resonance (SPR) of metal nanoparticles exhibits quantum behaviors as the size decreases owing to the transitions of quantized conduction electrons, but most studies are limited to the monotonous SPR blue-shift caused by off-resonant transitions. Here, we demonstrate the nonmonotonous SPR red-shift caused by resonant electron transitions and photocatalytic activity enhanced by the quantum plasmon resonance of colloidal gold nanoparticles. A maximal SPR wavelength and the largest photocatalytic activity are observed in the quantum regime for the first time for the gold nanoparticles with a diameter of 3.6 nm. Theoretical analysis based on a quantum-corrected model reveals the evolution of SPR with quantized electron transitions and well explains the nonmonotonous size-dependencies of the SPR wavelength and absorption efficiency. These findings have profound implications for the understanding of the quantum nature of the SPR of metal nanoparticles and their applications in areas ranging from photophysics to photochemistry.

  16. X-ray excited ZnS:Cu,Co afterglow nanoparticles for photodynamic activation

    NASA Astrophysics Data System (ADS)

    Ma, Lun; Zou, Xiaoju; Bui, Brian; Chen, Wei; Song, Kwang Hyun; Solberg, Timothy

    2014-07-01

    Copper and cobalt co-doped ZnS (ZnS:Cu,Co) afterglow nanoparticles were conjugated to photosensitizer tetrabromorhodamine-123 (TBrRh123) and efficient energy transfer from the nanoparticles to TBrRh123 was observed. In addition to their X-ray excited luminescence, the ZnS:Cu,Co nanoparticles also show long lasting afterglow, which continuously serve as a light source for photodynamic therapy (PDT) activation. Compared to TBrRh123 or ZnS:Cu,Co alone, the ZnS:Cu,Co-TBrRh123 conjugates show low dark toxicity but high X-ray induced toxicity to human prostate cancer cells. The results indicate that the ZnS:Cu,Co afterglow nanoparticles have a good potential for PDT activation.

  17. nanoparticles

    NASA Astrophysics Data System (ADS)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

    2014-10-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

  18. Fungicidal activity of silver nanoparticles against Alternaria brassicicola

    NASA Astrophysics Data System (ADS)

    Gupta, Deepika; Chauhan, Pratima

    2016-04-01

    This work highlighted the fungicidal properties of silver nanoparticles against Alternaria brassicicola. Alternaria brassicicola causes Black spot of Cauliflower, radish, cabbage, kale which results in sever agricultural loss. We treat the synthesised silver nanoparticles (AgNPs) of 10, 25, 50, 100 and 110 ppm concentrations against Alternaria brassicicola on PDA containing Petri dish. We calculated inhibitory rate (%) in order to evaluate the antifungal efficacy of silver nanoparticles against pathogens. Treatment with 100ppm AgNPs resulted in maximum inhibition of Alternaria brassicicola i.e.92.2%. 110ppm of AgNPS also shows the same result, therefore 100ppm AgNPs was treated as optimize concentration. AgNPs effectively inhibited the growth of a Alternaria brassicicola, which suggests that AgNPs could be used as fungicide in plant disease management. Further research and development are necessary to translate this technology into plant disease management strategies.

  19. In vitro antiplasmodial activity of PDDS-coated metal oxide nanoparticles against Plasmodium falciparum

    NASA Astrophysics Data System (ADS)

    Jacob Inbaneson, Samuel; Ravikumar, Sundaram

    2013-06-01

    Malaria is the most important parasitic disease, leading to annual death of about one million people and the Plasmodium falciparum develops resistant to well-established antimalarial drugs. The newest antiplasmodial drug from metal oxide nanoparticles helps in addressing this problem. Commercial nanoparticles such as Fe3O4, MgO, ZrO2, Al2O3 and CeO2 coated with PDDS and all the coated and non-coated nanoparticles were screened for antiplasmodial activity against P. falciparum. The Al2O3 nanoparticles (71.42 ± 0.49 μg ml-1) showed minimum level of IC50 value and followed by MgO (72.33 ± 0.37 μg ml-1) and Fe3O4 nanoparticles (77.23 ± 0.42 μg ml-1). The PDDS-Fe3O4 showed minimum level of IC50 value (48.66 ± 0.45 μg ml-1), followed by PDDS-MgO (60.28 ± 0.42 μg ml-1) and PDDS-CeO2 (67.06 ± 0.61 μg ml-1). The PDDS-coated metal oxide nanoparticles showed superior antiplasmodial activity than the non-PDDS-coated metal oxide nanoparticles. Statistical analysis reveals that, significant in vitro antiplasmodial activity ( P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the nanoparticles after 48 h of incubation. It is concluded from the present study that, the PDDS-Fe3O4 showed good antiplasmodial activity and it might be used for the development of antiplasmodial drugs.

  20. Synthesis, physical properties and catalytic activity of Cr-doped ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Djaja, Nadia Febiana; Noorhidayati, Annisa; Saleh, Rosari

    2016-03-01

    The present work studies the photocatalytic degradation of Cr-doped ZnO nanoparticles toward aqueous mixture of organic dyes, such as methyl orange, methylene blue and congo red. Cr-doped ZnO nanoparticles were synthesized using co-precipitation method and characterized by several method of measurements. Photocatalytic mechanism was investigated by measuring the photocatalytic degradation rate in the presence of scavenger. The results revealed that hydroxyl radical plays an important role in photocatalytic activity.

  1. Biosynthesis of silver nanoparticles using lingonberry and cranberry juices and their antimicrobial activity.

    PubMed

    Puišo, Judita; Jonkuvienė, Dovilė; Mačionienė, Irena; Šalomskienė, Joana; Jasutienė, Ina; Kondrotas, Rokas

    2014-09-01

    In this study lingonberry and cranberry juices were used for silver nanoparticle synthesis. The berry juices were characterized by total phenolics, total anthocyanins and benzoic acid content, respectively 1.9-2.7mg/ml, 55.2-83.4mg/l and 590.8-889.2mg/l. The synthesis of silver nanoparticles was performed at room temperature assisting in solutions irradiated by ultraviolet for 30min. Ultraviolet-visible (UV-vis) spectroscopy and microscopy confirmed the formation of nanoparticles as well as the dark red color of colloid of silver samples showed the formation of stable nanoparticles. Broad localized surface plasmon resonance (LSPR) peaks in UV-vis spectra indicated the formation of polydispersive silver nanoparticles and LSPR was observed at 485nm and 520nm for the silver nanoparticles synthesis using lingonberry and cranberry juices, respectively. The antimicrobial activity of silver nanoparticles was determined against the reference strains of microorganisms that could be found in food products: Staphylococcus aureus ATCC 25923, Salmonella typhimurium ATCC 13076, Listeria monocytogenes ATCC 19111, Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633, Candida albicans ATCC 10231 and foodborne B. cereus producing and non-producing enterotoxins. Silver nanoparticles showed a broad spectrum of antimicrobial activity and were most active against S. aureus ATCC 25923, B. subtilis ATCC 6633 and B. cereus ATCC 11778 reference cultures, and less active against C. albicans ATCC 10231 and foodborne B. cereus. It can be concluded that lingonberry and cranberry juices could be used as bioreductants for silver ions.

  2. Photochemical N-demethylation of alkaloids.

    PubMed

    Ripper, J A; Tiekink, E R; Scammells, P J

    2001-02-26

    Certain alkaloids were observed to undergo N-demethylation processes under photochemical conditions. Tropine, acetyltropine, tropinone, and atropine were cleanly N-demethylated upon treatment with tetraphenylporphin, oxygen, and light. Dextromethorphan also underwent a N-demethylation reaction, but reacted further to afford an imine. In contrast, 14-acyloxycodeinones underwent a photochemically induced tandem N-demethylation acyl migration.

  3. Size and shape dependant antifungal activity of gold nanoparticles: a case study of Candida.

    PubMed

    Wani, Irshad A; Ahmad, Tokeer; Manzoor, Nikhat

    2013-01-01

    A simple and economical sonochemical approach was employed for the synthesis of gold nanoparticles. The effect of the reducing agents has been studied on the particle size, morphology and properties at the same ultrasonic frequency under ambient conditions. Gold nanodiscs of average diameter of 25 nm were obtained using tinchloride (SnCl(2)) as a reducing agent, while sodium borohydride (NaBH(4)) produced polyhedral structures of the average size of 30 nm. The time evolution of the UV-visible absorption spectra of the gold nanostructures shows the origin of peaks due to higher order quadrupolar modes apart from the peaks of the in plane and out plane dipolar surface plasmon modes. Surface area studies reveal the much higher surface area of the gold nanodiscs (179.5 m(2)/g), than the gold nanoparticles (150.5m(2)/g) prepared by the sodium borohydride as the reducing agent. The gold nanoparticles exhibit excellent antifungal activity against the fungus, Candida. We investigated the effect of the gold nanoparticles on the H(+)-ATPase mediated H(+) pumping by various Candida species. Gold nanodiscs displayed the stronger fungicidal activity compared to the gold polyhedral nanoparticles. The two types of gold nanoparticles inhibit H(+)-ATPase activity at their respective MIC values.

  4. Catalase-only nanoparticles prepared by shear alone: Characteristics, activity and stability evaluation.

    PubMed

    Huang, Xiao-Nan; Du, Xin-Ying; Xing, Jin-Feng; Ge, Zhi-Qiang

    2016-09-01

    Catalase is a promising therapeutic enzyme; however, it carries risks of inactivation and rapid degradation when it is used in practical bioprocess, such as delivery in vivo. To overcome the issue, we made catalase-only nanoparticles using shear stress alone at a moderate shear rate of 217s(-1) in a coaxial cylinder flow cell. Properties of nanoparticles, including particle size, polydispersity index and zeta potential, were characterized. The conformational changes of pre- and post-sheared catalase were determined using spectroscopy techniques. The results indicated that the conformational changes of catalase and reduction in α-helical content caused by shear alone were less significant than that by desolvation method. Catalase-only nanoparticles prepared by single shear retained over 90% of its initial activity when compared with the native catalase. Catalase nanoparticles lost only 20% of the activity when stored in phosphate buffer solution for 72h at 4°C, whereas native catalase lost 53% under the same condition. Especially, the activity of nanogranulated catalase was decreased only slightly in the simulated intestinal fluid containing α-chymotrypsin during 4h incubation at 37°C, implying that the catalase nanoparticle was more resistant to the degradation of proteases than native catalase molecules. Overall, catalase-only nanoparticles offered a great potential to stabilize enzymes for various pharmaceutical applications.

  5. Electric-Field-Directed Self-Assembly of Active Enzyme-Nanoparticle Structures

    PubMed Central

    Hsiao, Alexander P.; Heller, Michael J.

    2012-01-01

    A method is presented for the electric-field-directed self-assembly of higher-order structures composed of alternating layers of biotin nanoparticles and streptavidin-/avidin-conjugated enzymes carried out on a microelectrode array device. Enzymes included in the study were glucose oxidase (GOx), horseradish peroxidase (HRP), and alkaline phosphatase (AP); all of which could be used to form a light-emitting microscale glucose sensor. Directed assembly included fabricating multilayer structures with 200 nm or 40 nm GOx-avidin-biotin nanoparticles, with AP-streptavidin-biotin nanoparticles, and with HRP-streptavidin-biotin nanoparticles. Multilayered structures were also fabricated with alternate layering of HRP-streptavidin-biotin nanoparticles and GOx-avidin-biotin nanoparticles. Results showed that enzymatic activity was retained after the assembly process, indicating that substrates could still diffuse into the structures and that the electric-field-based fabrication process itself did not cause any significant loss of enzyme activity. These methods provide a solution to overcome the cumbersome passive layer-by-layer assembly methods to efficiently fabricate higher-order active biological and chemical hybrid structures that can be useful for creating novel biosensors and drug delivery nanostructures, as well as for diagnostic applications. PMID:22500078

  6. Photocatalytic activity of SnO{sub 2} nanoparticles in methylene blue degradation

    SciTech Connect

    Kim, Sung Phil; Choi, Myong Yong; Choi, Hyun Chul

    2016-02-15

    Highlights: • Nanosized SnO{sub 2} photocatalysts were prepared with a precipitation method. • SnO{sub 2} nanoparticles displayed high photocatalytic activities for the MB degradation. • OH radicals are the main active species in photocatalysis on the SnO{sub 2} nanoparticles. - Abstract: Nanosized SnO{sub 2} photocatalysts were prepared with a precipitation method and were characterized by performing transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The powder XRD results revealed that the SnO{sub 2} nanoparticles have a typical tetragonal rutile (cassiterite) structure and the average crystallite size was found to be approximately 4.5 nm by using the Debye–Scherrer equation. The prepared SnO{sub 2} nanoparticles consist of agglomerated particles with a mean diameter of around 4–5 nm according to the analysis of TEM images. The XAS data confirmed that the prepared samples have cassiterite structures with tin oxidation state of +4. The prepared SnO{sub 2} nanoparticles were found to exhibit approximately 3.8 times higher activity than bulk SnO{sub 2} in the photodegradation of methylene blue. On the basis of a trapping experiment, we developed a possible mechanism for the photodegradation on SnO{sub 2} nanoparticles.

  7. Electric-field-directed self-assembly of active enzyme-nanoparticle structures.

    PubMed

    Hsiao, Alexander P; Heller, Michael J

    2012-01-01

    A method is presented for the electric-field-directed self-assembly of higher-order structures composed of alternating layers of biotin nanoparticles and streptavidin-/avidin-conjugated enzymes carried out on a microelectrode array device. Enzymes included in the study were glucose oxidase (GOx), horseradish peroxidase (HRP), and alkaline phosphatase (AP); all of which could be used to form a light-emitting microscale glucose sensor. Directed assembly included fabricating multilayer structures with 200 nm or 40 nm GOx-avidin-biotin nanoparticles, with AP-streptavidin-biotin nanoparticles, and with HRP-streptavidin-biotin nanoparticles. Multilayered structures were also fabricated with alternate layering of HRP-streptavidin-biotin nanoparticles and GOx-avidin-biotin nanoparticles. Results showed that enzymatic activity was retained after the assembly process, indicating that substrates could still diffuse into the structures and that the electric-field-based fabrication process itself did not cause any significant loss of enzyme activity. These methods provide a solution to overcome the cumbersome passive layer-by-layer assembly methods to efficiently fabricate higher-order active biological and chemical hybrid structures that can be useful for creating novel biosensors and drug delivery nanostructures, as well as for diagnostic applications.

  8. Comparative antibacterial activity of silver nanoparticles synthesised by biological and chemical routes with pluronic F68 as a stabilising agent.

    PubMed

    Santos, Carolina Alves Dos; Seckler, Marcelo Martins; Ingle, Avinash P; Rai, Mahendra

    2016-08-01

    The authors report the comparative antibacterial activity of silver nanoparticles synthesised by biological (using Fusarium oxysporum) and chemical routes in the presence and absence of pluronic F68 as a stabilising agent. The production of silver nanoparticles was evidenced by UV-visible spectra, with absorbance at about 420 nm in the case of both biological and chemical synthesis. X-ray diffraction pattern confirmed the presence of face-centred cubic structure (FCC plane). The nanoparticles characterised by transmission and scanning electron microscopy showed spherical silver nanoparticles with size range of 5-40 and 10-70 nm in the case of biologically and chemically synthesised nanoparticles, respectively. Addition of pluronic F68 showed the stabilisation of silver nanoparticles. Antibacterial efficacy of silver nanoparticles demonstrated different inhibitory activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Overall, biologically synthesised silver nanoparticles showed higher activity as compared with chemically synthesised nanoparticles. Silver nanoparticles synthesised in the presence of pluronic F68 by the chemical route exhibited synergism in antibacterial activity as compared with those synthesised without pluronic F68. On the contrary, biogenic silver nanoparticles without pluronic F68 showed higher antibacterial potential.

  9. Optimal activation of carboxyl-superparamagnetic iron oxide nanoparticles bioconjugated with antibody using orthogonal array design.

    PubMed

    Liu, Lin; Zhang, Xiaoqang; Zhang, Yu; Pu, Yuepu; Yin, Lihong; Tang, Meng; Liu, Hui

    2013-12-01

    This study aims to bioconjugate anti-EMMPRIN monoclonal antibody on the surface of carboxyl-SPIO nanoparticles and to optimize the activated conditions of bioconjugation. Anti-EMMPRIN monoclonal antibody bioconjugated carboxyl-SPIO nanoparticles were performed through a coupling strategy of EDC and sulfo-NHS. The procedure was comprised of two steps by activation of carboxyl-SPIO nanoparticles and conjugation with monoclonal antibody. The optimal activated parameters of bioconjugation were evaluated by single factor design and orthogonal array design. SDS-PAGE analysis and Bradford assay was used for testing and verifying the efficiency of activated conditions obtained from orthogonal array. The results show that pH value, temperature and reaction time were important factors that influence bioconjugated efficiency. The activated parameters with pH value 6.2, temperature 25 degrees C and reaction time 30 min were obviously optimal for activation of carboxyl-SPIO nanoparticles and conjugation with monoclonal EMMPEIN antibody. This coupling strategy for anti-EMMPRIN mAb bioconjugated on SPIO nanoparticles was efficient, and may be further applied in the fields of medical or biological practices.

  10. Transition-metal-doped ZnO nanoparticles: synthesis, characterization and photocatalytic activity under UV light.

    PubMed

    Saleh, Rosari; Djaja, Nadia Febiana

    2014-09-15

    ZnO nanoparticles doped with transition metals (Mn and Co) were prepared by a co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-rays, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy and diffuse reflectance spectroscopy. The photocatalytic activities of the transition-metal-doped ZnO nanoparticles were evaluated in the degradation of methyl orange under UV irradiation. ZnO nanoparticles doped with 12 at.% of Mn and Co ions exhibited the maximum photodegradation efficiency. The experiment also demonstrated that the photodegradation efficiency of Mn-doped ZnO nanoparticles was higher than that of Co-doped ZnO nanoparticles. These results indicate that charge trapping states due to the doping were the decisive factor rather than the average particle size and energy gap. Moreover the effect of pH values on the degradation efficiency was discussed in the photocatalytic experiments using 12 at.% Mn- and Co-doped ZnO nanoparticles.

  11. Magnesium oxide nanoparticles on green activated carbon as efficient CO2 adsorbent

    NASA Astrophysics Data System (ADS)

    Wan Isahak, Wan Nor Roslam; Ramli, Zatil Amali Che; Mohamed Hisham, Mohamed Wahab; Yarmo, Mohd Ambar

    2013-11-01

    This study was focused on carbon dioxide (CO2) adsorption ability using Magnesium oxide (MgO) nanoparticles and MgO nanoparticles supported activated carbon based bamboo (BAC). The suitability of MgO as a good CO2 adsorbent was clarified using Thermodynamic considerations (Gibbs-Helmholtz relationship). The ΔH and ΔG of this reaction were - 117.5 kJṡmol-1 and - 65.4 kJṡmol-1, respectively, at standard condition (298 K and 1 atm). The complete characterization of these adsorbent were conducted by using BET, XRD, FTIR, TEM and TPD-CO2. The surface areas for MgO nanoparticles and MgO nanoparticles supported BAC were 297.1 m2/g and 702.5 m2/g, respectively. The MgO nanoparticles supported BAC shown better physical and chemical adsorption ability with 39.8 cm3/g and 6.5 mmol/g, respectively. The combination of MgO nanoparticle and BAC which previously prepared by chemical method can reduce CO2 emissions as well as better CO2 adsorption behavior. Overall, our results indicate that nanoparticles of MgO on BAC posses unique surface chemistry and their high surface reactivity coupled with high surface area allowed them to approach the goal as an efficient CO2 adsorbent.

  12. Enhancement of antidandruff activity of shampoo by biosynthesized silver nanoparticles from Solanum trilobatum plant leaf

    NASA Astrophysics Data System (ADS)

    Pant, Gaurav; Nayak, Nitesh; Gyana Prasuna, R.

    2013-10-01

    The present investigation describes simple and effective method for synthesis of silver nanoparticles via green route. Solanum trilobatum Linn extract were prepared by both conventional and homogenization method. We optimized the production of silver nanoparticles under sunlight, microwave and room temperature. The best results were obtained with sunlight irradiation, exhibiting 15-20 nm silver nanoparticles having cubic and hexagonal shape. Biosynthesized nanoparticles were highly toxic to various bacterial strains tested. In this study we report antibacterial activity against various Gram negative ( Klebsiella pneumoniae, Vibrio cholerae and Salmonella typhi) and Gram positive ( Staphylococcus aureus, Bacillus cereus and Micrococcus luteus) bacterial strains. Screening was also performed for any antifungal properties of the nanoparticles against human pathogenic fungal strains ( Candida albicans and Candida parapsilosis). We also demonstrated that these nanoparticles when mixed with shampoo enhance the anti-dandruff effect against dandruff causing fungal pathogens ( Pityrosporum ovale and Pityrosporum folliculitis). The present study showed a simple, rapid and economical route to synthesize silver nanoparticles and their applications hence has a great potential in biomedical field.

  13. Magnesium oxide nanoparticles on green activated carbon as efficient CO{sub 2} adsorbent

    SciTech Connect

    Wan Isahak, Wan Nor Roslam; Ramli, Zatil Amali Che; Mohamed Hisham, Mohamed Wahab; Yarmo, Mohd Ambar

    2013-11-27

    This study was focused on carbon dioxide (CO{sub 2}) adsorption ability using Magnesium oxide (MgO) nanoparticles and MgO nanoparticles supported activated carbon based bamboo (BAC). The suitability of MgO as a good CO{sub 2} adsorbent was clarified using Thermodynamic considerations (Gibbs-Helmholtz relationship). The ΔH and ΔG of this reaction were − 117.5 kJ⋅mol{sup −1} and − 65.4 kJ⋅mol{sup −1}, respectively, at standard condition (298 K and 1 atm). The complete characterization of these adsorbent were conducted by using BET, XRD, FTIR, TEM and TPD−CO{sub 2}. The surface areas for MgO nanoparticles and MgO nanoparticles supported BAC were 297.1 m{sup 2}/g and 702.5 m{sup 2}/g, respectively. The MgO nanoparticles supported BAC shown better physical and chemical adsorption ability with 39.8 cm{sup 3}/g and 6.5 mmol/g, respectively. The combination of MgO nanoparticle and BAC which previously prepared by chemical method can reduce CO{sub 2} emissions as well as better CO{sub 2} adsorption behavior. Overall, our results indicate that nanoparticles of MgO on BAC posses unique surface chemistry and their high surface reactivity coupled with high surface area allowed them to approach the goal as an efficient CO{sub 2} adsorbent.

  14. Antibacterial Activity of Green Synthesized Silver Nanoparticles Using Vasaka (Justicia adhatoda L.) Leaf Extract.

    PubMed

    Bose, Debadin; Chatterjee, Someswar

    2015-06-01

    There is an increasing demand for silver nanoparticles due to its wide applicability in various area of biological science such as in field of antimicrobial and therapeutics, biosensing, drug delivery etc. To use in bioprocess the silver nanoparticles should be biocompatible and free from toxic chemicals. In the present study we report a cost effective and environment friendly route for green synthesis of silver nanoparticles using Vasaka (Justicia adhatoda L.) leaf extract as reducing as well as capping agent. This plant has been opted for the present study for its known medicinal properties and it is easily available. The biosynthesized silver nanoparticles are characterized by UV-Vis spectroscopy and TEM analysis. It is observed the nanoparticles are well shaped and the average particle size is 20 nm in the range of 5-50 nm. The antibacterial activity of these nanoparticles against Pseudomonas aeruginosa MTCC 741 has been measured by disc diffusion method, agar cup assay and serial dilution turbidity measurement assay. The results show green synthesized silver nanoparticles, using Vasaka leaf extract, have a potential to inhibit the growth of bacteria.

  15. "Synthesis, characterization and studies on antioxidant activity of silver nanoparticles using Elephantopus scaber leaf extract".

    PubMed

    Kharat, Sopan N; Mendhulkar, Vijay D

    2016-05-01

    The simple, eco-friendly and cost effective method of green synthesis of silver nanoparticle in the leaf extract of medicinal plant Elephantopus scaber L. is illustrated in the present work. The synthesized silver nanoparticles (AgNPs) were characterized with UV-Vis-spectroscopy, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The UV-spectra show maximum absorbance at 435 nm, NTA analysis shows 78 nm average sizes of nanoparticles, TEM analysis indicates spherical shape of the nanoparticles with the average diameter of 50 nm. The XRD peaks at 2θ range of 30-80° correspond to (111), (200), (220), (311) reflection planes that indicate the structure of metallic silver. FTIR analysis reveals surface capping of phenolic groups. Existence of peaks in the range of 1611 to 1400 cm(-1) indicates the presence of aromatic rings in the leaf extract. The peak at 1109 cm(-1) is due to the presence of OH groups. The antioxidant activity of synthesized nanoparticles was evaluated performing DPPH assay and it is observed that the photosynthesized nanoparticle also possesses antioxidant potentials. Thus, it can be used as potential free radical scavenger. Silver particles have tremendous applications in the field of diagnostics and therapeutics. To this context, the surface coating of plant metabolite constituents has great potentials. Therefore, the present work has been undertaken to synthesize the AgNPs using leaf extract of medicinal plant, E. scaber, to characterize and access their antioxidant properties.

  16. Chitosan nanoparticles enhances the anti-quorum sensing activity of kaempferol.

    PubMed

    Ilk, Sedef; Sağlam, Necdet; Özgen, Mustafa; Korkusuz, Feza

    2017-01-01

    Quorum sensing (QS) is a cell density dependent expression of species in bacteria mediated by compounds called autoinducers (AI). Several processes responsible for successful establishment of bacterial infection are mediated by QS. Inhibition of QS is therefore being considered as a new target for antimicrobial chemotherapy. Flavonoid compounds are strong antioxidant and antimicrobial agents but their applications are limited due to their poor dissolution and bioavailability. Our objective was to investigate the effect of kaempferol loaded chitosan nanoparticles on modulating QS mediated by AI in model bioassay test systems. For this purpose, kaempferol loaded nanoparticles were synthesized and characterized in terms of hydrodynamic diameter, hydrogen bonding, amorphous transformation and antioxidant activity. QS inhibition in time dependent manner of nanoparticles was measured in violacein pigment producing using the biosensor strain Chromobacterium violaceum CV026 mediated by AI known as acylated homoserine lactone (AHL). Our results indicated that the average kaempferol loaded chitosan/TPP nanoparticle size and zeta potential were 192.27±13.6nm and +35mV, respectively. The loading and encapsulation efficiency of kaempferol into chitosan/TPP nanoparticles presented higher values between 78 and 93%. Kaempferol loaded chitosan/TPP nanoparticle during the 30 storage days significantly inhibited the production of violacein pigment in Chromobacterium violaceum CV026. The observation that kaempferol encapsulated chitosan nanoparticles can inhibit QS related processes opens up an exciting new strategy for antimicrobial chemotherapy as stable QS-based anti-biofilm agents.

  17. Transition-metal-doped ZnO nanoparticles: Synthesis, characterization and photocatalytic activity under UV light

    NASA Astrophysics Data System (ADS)

    Saleh, Rosari; Djaja, Nadia Febiana

    2014-09-01

    ZnO nanoparticles doped with transition metals (Mn and Co) were prepared by a co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-rays, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy and diffuse reflectance spectroscopy. The photocatalytic activities of the transition-metal-doped ZnO nanoparticles were evaluated in the degradation of methyl orange under UV irradiation. ZnO nanoparticles doped with 12 at.% of Mn and Co ions exhibited the maximum photodegradation efficiency. The experiment also demonstrated that the photodegradation efficiency of Mn-doped ZnO nanoparticles was higher than that of Co-doped ZnO nanoparticles. These results indicate that charge trapping states due to the doping were the decisive factor rather than the average particle size and energy gap. Moreover the effect of pH values on the degradation efficiency was discussed in the photocatalytic experiments using 12 at.% Mn- and Co-doped ZnO nanoparticles.

  18. Targeting of peptide conjugated magnetic nanoparticles to urokinase plasminogen activator receptor (uPAR) expressing cells

    NASA Astrophysics Data System (ADS)

    Hansen, Line; Unmack Larsen, Esben Kjær; Nielsen, Erik Holm; Iversen, Frank; Liu, Zhuo; Thomsen, Karen; Pedersen, Michael; Skrydstrup, Troels; Nielsen, Niels Chr.; Ploug, Michael; Kjems, Jørgen

    2013-08-01

    Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are currently being used as a magnetic resonance imaging (MRI) contrast agent in vivo, mainly by their passive accumulation in tissues of interest. However, a higher specificity can ideally be achieved when the nanoparticles are targeted towards cell specific receptors and this may also facilitate specific drug delivery by an enhanced target-mediated endocytosis. We report efficient peptide-mediated targeting of magnetic nanoparticles to cells expressing the urokinase plasminogen activator receptor (uPAR), a surface biomarker for poor patient prognosis shared by several cancers including breast, colorectal, and gastric cancers. Conjugation of a uPAR specific targeting peptide onto polyethylene glycol (PEG) coated USPIO nanoparticles by click chemistry resulted in a five times higher uptake in vitro in a uPAR positive cell line compared to nanoparticles carrying a non-binding control peptide. In accordance with specific receptor-mediated recognition, a low uptake was observed in the presence of an excess of ATF, a natural ligand for uPAR. The uPAR specific magnetic nanoparticles can potentially provide a useful supplement for tumor patient management when combined with MRI and drug delivery.Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are currently being used as a magnetic resonance imaging (MRI) contrast agent in vivo, mainly by their passive accumulation in tissues of interest. However, a higher specificity can ideally be achieved when the nanoparticles are targeted towards cell specific receptors and this may also facilitate specific drug delivery by an enhanced target-mediated endocytosis. We report efficient peptide-mediated targeting of magnetic nanoparticles to cells expressing the urokinase plasminogen activator receptor (uPAR), a surface biomarker for poor patient prognosis shared by several cancers including breast, colorectal, and gastric cancers. Conjugation of a uPAR specific

  19. Evaluation of cytotoxicity, immune compatibility and antibacterial activity of biogenic silver nanoparticles.

    PubMed

    Składanowski, M; Golinska, P; Rudnicka, K; Dahm, H; Rai, M

    2016-12-01

    The study was focused on assessment of antibacterial activity, cytotoxicity and immune compatibility of biogenic silver nanoparticles (AgNPs) synthesized from Streptomyces sp. NH28 strain. Nanoparticles were biosynthesized and characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, nanoparticle tracking analysis system and zeta potential. Antibacterial activity was tested against Gram-positive and Gram-negative bacteria; minimal inhibitory concentration was recorded. Cytotoxicity was estimated using L929 mouse fibroblasts via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Biocompatibility of AgNPs was performed using THP1-XBlue™ cells. Biogenic AgNPs presented high antibacterial activity against all tested bacteria. Minimum inhibitory concentration of AgNPs against bacterial cells was found to be in range of 1.25-10 μg/mL. Silver nanoparticles did not show any harmful interaction to mouse fibroblast cell line, and no activation of nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) cells was observed at concentration below 10 µg/mL. The half-maximal inhibitory concentration (IC50) value was established at 64.5 μg/mL. Biological synthesis of silver can be used as an effective system for formation of metal nanoparticles. Biosynthesized AgNPs can be used as an antibacterial agent, which can be safe for eukaryotic cells.

  20. Antimicrobial activity and physical characterization of silver nanoparticles green synthesized using nitrate reductase from Fusarium oxysporum.

    PubMed

    Gholami-Shabani, Mohammadhassan; Akbarzadeh, Azim; Norouzian, Dariush; Amini, Abdolhossein; Gholami-Shabani, Zeynab; Imani, Afshin; Chiani, Mohsen; Riazi, Gholamhossein; Shams-Ghahfarokhi, Masoomeh; Razzaghi-Abyaneh, Mehdi

    2014-04-01

    Nanostructures from natural sources have received major attention due to wide array of biological activities and less toxicity for humans, animals, and the environment. In the present study, silver nanoparticles were successfully synthesized using a fungal nitrate reductase, and their biological activity was assessed against human pathogenic fungi and bacteria. The enzyme was isolated from Fusarium oxysporum IRAN 31C after culturing on malt extract-glucose-yeast extract-peptone (MGYP) medium. The enzyme was purified by a combination of ultrafiltration and ion exchange chromatography on DEAE Sephadex and its molecular weight was estimated by gel filtration on Sephacryl S-300. The purified enzyme had a maximum yield of 50.84 % with a final purification of 70 folds. With a molecular weight of 214 KDa, it is composed of three subunits of 125, 60, and 25 KDa. The purified enzyme was successfully used for synthesis of silver nanoparticles in a way dependent upon NADPH using gelatin as a capping agent. The synthesized silver nanoparticles were characterized by X-ray diffraction, dynamic light scattering spectroscopy, and transmission and scanning electron microscopy. These stable nonaggregating nanoparticles were spherical in shape with an average size of 50 nm and a zeta potential of -34.3. Evaluation of the antimicrobial effects of synthesized nanoparticles by disk diffusion method showed strong growth inhibitory activity against all tested human pathogenic fungi and bacteria as evident from inhibition zones that ranged from 14 to 25 mm. Successful green synthesis of biologically active silver nanoparticles by a nitrate reductase from F. oxysporum in the present work not only reduces laborious downstream steps such as purification of nanoparticle from interfering cellular components, but also provides a constant source of safe biologically-active nanomaterials with potential application in agriculture and medicine.

  1. Nanoparticles in photodynamic therapy: an emerging paradigm.

    PubMed

    Chatterjee, Dev Kumar; Fong, Li Shan; Zhang, Yong

    2008-12-14

    Photodynamic therapy (PDT) has emerged as one of the important therapeutic options in management of cancer and other diseases [M. Triesscheijn, P. Baas, J.H. Schellens, F.A. Stewart, Photodynamic therapy in oncology, Oncologist 11 (2006) 1034-1044]. Most photosensitizers are highly hydrophobic and require delivery systems. Previous classification of delivery systems was based on presence or absence of a targeting molecule on the surface [Y.N. Konan, R. Gurny, E. Allemann, State of the art in the delivery of photosensitizers for photodynamic therapy, J. Photochem. Photobiol., B 66 (2002) 89-106]. Recent reports have described carrier nanoparticles with additional active complementary and supplementary roles in PDT. We introduce a functional classification for nanoparticles in PDT to divide them into passive carriers and active participants in photosensitizer excitation. Active nanoparticles are distinguished from non-biodegradable carriers with extraneous functions, and sub-classified mechanistically into photosensitizer nanoparticles, [A.C. Samia, X. Chen, C. Burda, Semiconductor quantum dots for photodynamic therapy, J. Am. Chem. Soc. 125 (2003) 15736-15737, R. Bakalova, H. Ohba, Z. Zhelev, M. Ishikawa, Y. Baba, Quantum dots as photosensitizers? Nat. Biotechnol. 22 (2004) 1360-1361] self-illuminating nanoparticles [W. Chen, J. Zhang, Using nanoparticles to enable simultaneous radiation and photodynamic therapies for cancer treatment, J. Nanosci. Nanotechnology 6 (2006) 1159-1166] and upconverting nanoparticles [P. Zhang, W. Steelant, M. Kumar, M. Scholfield, Versatile photosensitizers for photodynamic therapy at infrared excitation, J. Am. Chem. Soc. 129 (2007) 4526-4527]. Although several challenges remain before they can be adopted for clinical use, these active or second-generation PDT nanoparticles probably offer the best hope for extending the reach of PDT to regions deep in the body.

  2. Effects of nanoparticle coatings on the activity of oncolytic adenovirus-magnetic nanoparticle complexes.

    PubMed

    Tresilwised, Nittaya; Pithayanukul, Pimolpan; Holm, Per Sonne; Schillinger, Ulrike; Plank, Christian; Mykhaylyk, Olga

    2012-01-01

    Limitations to adenovirus infectivity can be overcome by association with magnetic nanoparticles and enforced infection by magnetic field influence. Here we examined three core-shell-type iron oxide magnetic nanoparticles differing in their surface coatings, particle sizes and magnetic properties for their ability to enhance the oncolytic potency of adenovirus Ad520 and to stabilize it against the inhibitory effects of serum or a neutralizing antibody. It was found that the physicochemical properties of magnetic nanoparticles are critical determinants of the properties which govern the oncolytic productivities of their complexes with Ad520. Although high serum concentration during infection or a neutralizing antibody had strong inhibitory influence on the uptake or oncolytic productivity of the naked virus, one particle type was identified which conferred high protection against both inhibitory factors while enhancing the oncolytic productivity of the internalized virus. This particle type equipped with a silica coating and adsorbed polyethylenimine, displaying a high magnetic moment and high saturation magnetization, mediated a 50% reduction of tumor growth rate versus control upon intratumoral injection of its complex with Ad520 and magnetic field influence, whereas Ad520 alone was inefficient. The correlations between physical properties of the magnetic particles or virus complexes and oncolytic potency are described herein.

  3. Synthesis of Silver Nanoparticles Using Hydroxyl Functionalized Ionic Liquids and Their Antimicrobial Activity

    PubMed Central

    Dorjnamjin, Demberelnyamba; Ariunaa, Maamaa; Shim, Young Key

    2008-01-01

    We report a new one phase method for the synthesis of uniform monodisperse crystalline Ag nanoparticles in aqueous systems that has been developed by using newly synthesized mono and dihydroxylated ionic liquids and cationic surfactants based on 1,3-disubstituted imidazolium cations and halogens anions. The hydroxyl functionalized ionic liquids (HFILs) and hydroxyl functionalized cationic surfactants (HFCSs) also simultaneously acts both as the reductant and protective agent. By changing the carbon chain length, alcohol structure and anion of the 1,3-imidazolium based HFILs and HFCSs the particle size, uniform and dispersibility of nanoparticles in aqueous solvents could be controlled. Transmission electron microscopy (TEM), electron diffraction, UV-Vis and NMR, were used for characterization of HFILs, HFCSs and silver nanoparticles. TEM studies on the solution showed representative spherical silver nanoparticles with average sizes 2–8 nm, particularly 2.2 nm and 4.5 nm in size range and reasonable narrow particle size distributions (SD-standard distribution) 0.2 nm and 0.5 nm respectively. The all metal nanoparticles are single crystals with face centered cubic (fcc) structure. The silver nanoparticles surface of plasmon resonance band (λmax) around 420 nm broadened and little moved to the long wavelength region that indicating the formation of silver nanoparticles dispersion with broad absorption around infrared (IR) region. Silver complexes of these HFILs as well as different silver nanoparticles dispersions have been tested in vitro against several gram positive and gram negative bacteria and fungus. The silver nanoparticles providing environmentally friendly and high antimicrobial activity agents. PMID:19325785

  4. Synthesis of silver nanoparticles using hydroxyl functionalized ionic liquids and their antimicrobial activity.

    PubMed

    Dorjnamjin, Demberelnyamba; Ariunaa, Maamaa; Shim, Young Key

    2008-05-01

    We report a new one phase method for the synthesis of uniform monodisperse crystalline Ag nanoparticles in aqueous systems that has been developed by using newly synthesized mono and dihydroxylated ionic liquids and cationic surfactants based on 1,3-disubstituted imidazolium cations and halogens anions. The hydroxyl functionalized ionic liquids (HFILs) and hydroxyl functionalized cationic surfactants (HFCSs) also simultaneously acts both as the reductant and protective agent. By changing the carbon chain length, alcohol structure and anion of the 1,3-imidazolium based HFILs and HFCSs the particle size, uniform and dispersibility of nanoparticles in aqueous solvents could be controlled. Transmission electron microscopy (TEM), electron diffraction, UV-Vis and NMR, were used for characterization of HFILs, HFCSs and silver nanoparticles. TEM studies on the solution showed representative spherical silver nanoparticles with average sizes 2-8 nm, particularly 2.2 nm and 4.5 nm in size range and reasonable narrow particle size distributions (SD-standard distribution) 0.2 nm and 0.5 nm respectively. The all metal nanoparticles are single crystals with face centered cubic (fcc) structure. The silver nanoparticles surface of plasmon resonance band (lambda(max)) around 420 nm broadened and little moved to the long wavelength region that indicating the formation of silver nanoparticles dispersion with broad absorption around infrared (IR) region. Silver complexes of these HFILs as well as different silver nanoparticles dispersions have been tested in vitro against several gram positive and gram negative bacteria and fungus. The silver nanoparticles providing environmentally friendly and high antimicrobial activity agents.

  5. Isoprene: a photochemical kinetic mechanism

    SciTech Connect

    Killus, J.P.; Whitten, G.Z.

    1984-03-01

    A computer-modeling study has produced a photochemical kinetic mechanism for the atmospheric chemistry of isoprene, a naturally occurring common constituent of the troposphere. The kinetic mechnism is ready for use in atmospheric models because the reactions described are shown to adequately reproduce the results of a series of outdoor smog chamber experiments which encompass a wide range of precursor conditions of isoprene and NO/sub x/. Isoprene is a very reactive molecule that can contribute as much as 50% of the overall reactivity of rural air even though isoprene might be only 6% of the ambient hydrocarbon level. The major intermediate products of the atmospheric oxidation of isoprene, methyl vinyl ketone, methacrolein, methylglyoxal, and formaldehyde are also highly reactive. 25 references.

  6. Particle-Cell Contact Enhances Antibacterial Activity of Silver Nanoparticles

    PubMed Central

    Bondarenko, Olesja; Ivask, Angela; Käkinen, Aleksandr; Kurvet, Imbi; Kahru, Anne

    2013-01-01

    Background It is generally accepted that antibacterial properties of Ag nanoparticles (AgNPs) are dictated by their dissolved fraction. However, dissolution-based concept alone does not fully explain the toxic potency of nanoparticulate silver compared to silver ions. Methodology/Principal Findings Herein, we demonstrated that the direct contact between bacterial cell and AgNPs' surface enhanced the toxicity of nanosilver. More specifically, cell-NP contact increased the cellular uptake of particle-associated Ag ions – the single and ultimate cause of toxicity. To prove that, we evaluated the toxicity of three different AgNPs (uncoated, PVP-coated and protein-coated) to six bacterial strains: Gram-negative Escherichia coli, Pseudomonas fluorescens, P. putida and P. aeruginosa and Gram-positive Bacillus subtilis and Staphylococcus aureus. While the toxicity of AgNO3 to these bacteria varied only slightly (the 4-h EC50 ranged from 0.3 to 1.2 mg Ag/l), the 4-h EC50 values of protein-coated AgNPs for various bacterial strains differed remarkably, from 0.35 to 46 mg Ag/l. By systematically comparing the intracellular and extracellular free Ag+ liberated from AgNPs, we demonstrated that not only extracellular dissolution in the bacterial test environment but also additional dissolution taking place at the particle-cell interface played an essential role in antibacterial action of AgNPs. The role of the NP-cell contact in dictating the antibacterial activity of Ag-NPs was additionally proven by the following observations: (i) separation of bacterial cells from AgNPs by particle-impermeable membrane (cut-off 20 kDa, ∼4 nm) significantly reduced the toxicity of AgNPs and (ii) P. aeruginosa cells which tended to attach onto AgNPs, exhibited the highest sensitivity to all forms of nanoparticulate Ag. Conclusions/Significance Our findings provide new insights into the mode of antibacterial action of nanosilver and explain some discrepancies in this field, showing that

  7. Entrapped elemental selenium nanoparticles affect physicochemical properties of selenium fed activated sludge.

    PubMed

    Jain, Rohan; Seder-Colomina, Marina; Jordan, Norbert; Dessi, Paolo; Cosmidis, Julie; van Hullebusch, Eric D; Weiss, Stephan; Farges, François; Lens, Piet N L

    2015-09-15

    Selenite containing wastewaters can be treated in activated sludge systems, where the total selenium is removed from the wastewater by the formation of elemental selenium nanoparticles, which are trapped in the biomass. No studies have been carried out so far on the characterization of selenium fed activated sludge flocs, which is important for the development of this novel selenium removal process. This study showed that more than 94% of the trapped selenium in activated sludge flocs is in the form of elemental selenium, both as amorphous/monoclinic selenium nanospheres and trigonal selenium nanorods. The entrapment of the elemental selenium nanoparticles in the selenium fed activated sludge flocs leads to faster settling rates, higher hydrophilicity and poorer dewaterability compared to the control activated sludge (i.e., not fed with selenite). The selenium fed activated sludge showed a less negative surface charge density as compared to the control activated sludge. The presence of trapped elemental selenium nanoparticles further affected the spatial distribution of Al and Mg in the activated sludge flocs. This study demonstrated that the formation and subsequent trapping of elemental selenium nanoparticles in the activated sludge flocs affects their physicochemical properties.

  8. Preparation of graphene-Ag nanoparticles hybrids and their SERS activities

    NASA Astrophysics Data System (ADS)

    Wang, Xinyu; Wang, Ning; Gong, Tiancheng; Zhu, Yong; Zhang, Jie

    2016-11-01

    Surface-enhanced Raman scattering (SERS) substrates based on graphene and Ag nanoparticles hybrid structures with low cost, high uniformity were prepared by a standard process of immobilization of silver nanoparticles with 3-aminopropyltrimethoxysilane (APTMS). Thermal annealing was used for removing residual APTMS and adjusting the morphology of silver nanoparticles, and the effectiveness of this method was verified experimentally. The influence of annealing temperature, dipping duration, and APTMS volume on the distribution of Ag nanoparticles and Raman enhancement was investigated experimentally and analyzed in detail. Our samples were prepared under the preparation conditions of 10% ν/ν APTMS, dipping time of 48 h, annealing temperature of 450 °C, duration of 30 min, and Ar flow rate of 40 sccm. SERS activities with enhancement of 107 and relative standard deviation of <20% were observed using rhodamine 6G (R6G) as probe molecule with a concentration of 10-6 M and 10-7 M.

  9. Facile synthesis and photocatalytic activity of bi-phase dispersible Cu-ZnO hybrid nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Liu, HongLing; Zhang, WenXing; Li, XueMei; Fang, Ning; Wang, XianHong; Wu, JunHua

    2015-04-01

    Bi-phase dispersible Cu-ZnO hybrid nanoparticles were synthesized by one-pot non-aqueous nanoemulsion with the use of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The transmission electron microscopy (TEM) and X-ray diffraction (XRD) show high crystallinity of the Cu-ZnO hybrid nanoparticles and an average particle size of ~19.4 nm. The ultraviolet-visible light absorbance spectrometry (UV-vis) and photoluminescence spectrophotometry (PL) demonstrate well dispersibility and excellent optical performance of Cu-ZnO hybrid nanoparticles both in organic and aqueous solvent. The X-ray photoelectron spectroscopy (XPS) confirms Cu1+ and Cu2+ in ZnO. The observation using Sudan red (III) as probe molecule reveals that the Cu-ZnO hybrid nanoparticles possess enhanced photocatalytic activity and stability which are promising for potential applications in photocatalysis.

  10. Surface properties, simultaneous photocatalytic and magnetic activities of Ni2FeVO6 nanoparticles

    NASA Astrophysics Data System (ADS)

    Qiao, Xuebin; Huang, Yanlin; Cheng, Han; Seo, Hyo Jin

    2015-12-01

    Nickel-ferro-vanadium oxide Ni2FeVO6 nanoparticles were prepared by the sol-gel film coating and subsequent sintering method. The phase formation was investigated X-ray polycrystalline diffraction (XRD) measurement. The surface characteristics were measured by scanning electron microscope (SEM), transmission electron microscopy (TEM), specific surface area, energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). This vanadate has a narrow band-gap energy of 1.784 eV. The investigations concluded that Ni2FeVO6 nanoparticles have photocatalytic ability under visible-light irradiation. The ferromagnetic behavior of the nanoparticles was confirmed by the magnetic hysteresis loops. The nanoparticles can be magnetically recoverable after photocatalytic reactions. The photocatalytic activities were discussed on the base of the multivalent cations in crystal lattices.

  11. Phoenix dactylifera L. leaf extract phytosynthesized gold nanoparticles; controlled synthesis and catalytic activity.

    PubMed

    Zayed, Mervat F; Eisa, Wael H

    2014-01-01

    A green synthesis route was reported to explore the reducing and capping potential of Phoenix dactylifera extract for the synthesis of gold nanoparticles. The processes of nucleation and growth of gold nanoparticles were followed by monitoring the absorption spectra during the reaction. The size and morphology of these nanoparticles was typically imaged using transmission electron microscopy (TEM). The particle size ranged between 32 and 45 nm and are spherical in shape. Fourier transform infrared (FTIR) analysis suggests that the synthesized gold nanoparticles might be stabilized through the interactions of hydroxyl and carbonyl groups in the carbohydrates, flavonoids, tannins and phenolic acids present in P. dactylifera. The as-synthesized Au colloids exhibited good catalytic activity for the degradation of 4-nitrophenol.

  12. Enhancing stability and photocatalytic activity of ZnO nanoparticles by surface modification of graphene oxide.

    PubMed

    Wang, Yinjie; Liu, Jincheng; Liu, Lei; Sun, Darren D

    2012-05-01

    This work reports a simple method for the preparation of high-quality GO-ZnO nanocomposite materials. Transmission electron microscopy (TEM) revealed that the ZnO nanoparticles are uniformly distributed on the GO sheets and the diameter of the ZnO nanoparticles falls in 5-8 nm. Further experimental results imply that involving GO sheets into the system could remarkably prevent the aggregation of ZnO nanoparticles compared to pure ZnO. The photocatalytic activity and stability of the prepared GO-ZnO composite for the degradation of Acid Orange 7 (AO 7) under UV light irradiation is significantly enhanced in comparison to the as-synthesized pristine ZnO nanoparticles. Considering the high photocatalytic acitivity and relative stability, this high-quality GO-ZnO nanocomposite is beneficial for the applications in environmental engineering and other fields.

  13. Controlled green synthesis of silver nanoparticles by Allium cepa and Musa acuminata with strong antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Sahni, Geetika; Panwar, Amit; Kaur, Balpreet

    2015-02-01

    A controlled "green synthesis" approach to synthesize silver nanoparticles by Allium cepa and Musa acuminata plant extract has been reported. The effect of different process parameters, such as pH, temperature and time, on synthesis of Ag nanoparticles from plant extracts has been highlighted. The work reports an easy approach to control the kinetics of interaction of metal ions with reducing agents, stabilized by ammonia to achieve sub-10 nm particles with narrow size distribution. The nanoparticles have been characterized by UV-Visible spectra and TEM analysis. Excellent antimicrobial activity at extremely low concentration of the nanoparticles was observed against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Fusarium oxysporum which may allow their exploitation as a new generation nanoproduct in biomedical and agricultural applications.

  14. Phoenix dactylifera L. leaf extract phytosynthesized gold nanoparticles; controlled synthesis and catalytic activity

    NASA Astrophysics Data System (ADS)

    Zayed, Mervat F.; Eisa, Wael H.

    2014-03-01

    A green synthesis route was reported to explore the reducing and capping potential of Phoenix dactylifera extract for the synthesis of gold nanoparticles. The processes of nucleation and growth of gold nanoparticles were followed by monitoring the absorption spectra during the reaction. The size and morphology of these nanoparticles was typically imaged using transmission electron microscopy (TEM). The particle size ranged between 32 and 45 nm and are spherical in shape. Fourier transform infrared (FTIR) analysis suggests that the synthesized gold nanoparticles might be stabilized through the interactions of hydroxyl and carbonyl groups in the carbohydrates, flavonoids, tannins and phenolic acids present in P. dactylifera. The as-synthesized Au colloids exhibited good catalytic activity for the degradation of 4-nitrophenol.

  15. Investigation of Water-Soluble X-ray Luminescence Nanoparticles for Photodynamic Activation

    SciTech Connect

    Liu, Yuanfang; Chen, Wei; Wang, Shaopeng; Joly, Alan G.

    2008-01-28

    In this letter, we report the synthesis of LaF3:Tb3+-MTCP (meso-Tetra(4-carboxyphenyl) porphine) nanoparticle conjugates and investigate the energy transfer as well as singlet oxygen generation following X-ray irradiation. Our observations indicate that LaF3:Tb3+-MTCP nanoparticle conjugates are efficient photodynamic agents that can be initiated by X-rays at a reasonably low dose. The addition of folic acid to facilitate targeting to folate receptors on tumor cells has no effect on the quantum yield of singlet oxygen in the nanoparticle-MTCP conjugates. Our pilot studies indicate that water-soluble scintillation nanoparticles can be potentially used to activate photodynamic therapy as a promising deep cancer treatment.

  16. Plant-mediated synthesis of biosilver nanoparticles using Pandanus amaryllifolius extract and its bactericidal activity

    SciTech Connect

    Akhir, Rabiatuladawiyah Md.; Fairuzi, Afiza Ahmad; Ismail, Nur Hilwani

    2015-08-28

    In this work, we describe a cost effective, easily scaled up and environmental friendly technique for green synthesis of silver nanoparticles (AgNPs) from 5 mM AgNO{sub 3} solution using aqueous extract of Pandanus amaryllifolius (P. amaryllifolius) leaves as reducing agent. Biosynthesized silver nanoparticles was confirmed by sampling the reaction mixture at regular intervals and the absorption maxima was scanned by Ultraviolet-Visible (UV-Vis) spectroscopy at wavelength of 200-500 nm. Images from Field Emission Scanning Electron Microscope (FESEM) have shown that the silver nanoparticles are 17-30 nm in range and assembled in mostly spherical shape. Elemental composition analysis by using Energy Dispersive X-ray (EDX) confirmed the presence of silver. Low concentration of biosynthesized silver nanoparticles have been found to exhibit good antibacterial activity against Staphylococcus aureus bacteria with average mean diameter of zone of inhibition (ZOI) of 16 mm.

  17. Facile synthesis and photocatalytic activity of bi-phase dispersible Cu-ZnO hybrid nanoparticles.

    PubMed

    Liu, Xiao; Liu, HongLing; Zhang, WenXing; Li, XueMei; Fang, Ning; Wang, XianHong; Wu, JunHua

    2015-01-01

    Bi-phase dispersible Cu-ZnO hybrid nanoparticles were synthesized by one-pot non-aqueous nanoemulsion with the use of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The transmission electron microscopy (TEM) and X-ray diffraction (XRD) show high crystallinity of the Cu-ZnO hybrid nanoparticles and an average particle size of ~19.4 nm. The ultraviolet-visible light absorbance spectrometry (UV-vis) and photoluminescence spectrophotometry (PL) demonstrate well dispersibility and excellent optical performance of Cu-ZnO hybrid nanoparticles both in organic and aqueous solvent. The X-ray photoelectron spectroscopy (XPS) confirms Cu(1+) and Cu(2+) in ZnO. The observation using Sudan red (III) as probe molecule reveals that the Cu-ZnO hybrid nanoparticles possess enhanced photocatalytic activity and stability which are promising for potential applications in photocatalysis.

  18. Plant-mediated synthesis of biosilver nanoparticles using Pandanus amaryllifolius extract and its bactericidal activity

    NASA Astrophysics Data System (ADS)

    Akhir, Rabiatuladawiyah Md.; Fairuzi, Afiza Ahmad; Ismail, Nur Hilwani

    2015-08-01

    In this work, we describe a cost effective, easily scaled up and environmental friendly technique for green synthesis of silver nanoparticles (AgNPs) from 5 mM AgNO3 solution using aqueous extract of Pandanus amaryllifolius (P. amaryllifolius) leaves as reducing agent. Biosynthesized silver nanoparticles was confirmed by sampling the reaction mixture at regular intervals and the absorption maxima was scanned by Ultraviolet-Visible (UV-Vis) spectroscopy at wavelength of 200-500 nm. Images from Field Emission Scanning Electron Microscope (FESEM) have shown that the silver nanoparticles are 17-30 nm in range and assembled in mostly spherical shape. Elemental composition analysis by using Energy Dispersive X-ray (EDX) confirmed the presence of silver. Low concentration of biosynthesized silver nanoparticles have been found to exhibit good antibacterial activity against Staphylococcus aureus bacteria with average mean diameter of zone of inhibition (ZOI) of 16 mm.

  19. Evaluation of the photocatalytic activity of iron oxide nanoparticles functionalized with titanium dioxide

    NASA Astrophysics Data System (ADS)

    Herrera, A.; Reyes, A.; Colina-Márquez, J.

    2016-02-01

    Photocatalytic activity of iron oxide (IO) nanoparticles functionalized with TiO2 was evaluated through photodegradation of phenol under UV irradiation. For this, magnetic nanoparticles were synthesized by co-precipitation method obtaining aggregates with a size of 46nm. The IO nanoparticles were encapsulated in a polysiloxane matrix and then functionalized with TiO2 at 25°C (sample A: 0.1g TiO2 and B: 0.3g TiO2). Photodegradation experiments were carried out for six hours at pH 3.0 using concentrations of IO-TiO2 nanoparticles of 0.2, 0.5, and 1.0g/L. A maximum amount of 89% of phenol photodegradation was achieved by using 0.2g/L of the IO-TiO2-B sample. In addition, it was evaluated the possibility to re-using the nanomaterial after magnetic separation. For this, 0.2g/L of B sample were submitted for five cycles of photodegradation. A stable photocatalytic activity was observed as well as the nanoparticles were regenerated by calcination among cycles, which suggests the versatility of these nanoparticles for the photodegradation of organic pollutants.

  20. Tannic acid modified silver nanoparticles show antiviral activity in herpes simplex virus type 2 infection.

    PubMed

    Orlowski, Piotr; Tomaszewska, Emilia; Gniadek, Marianna; Baska, Piotr; Nowakowska, Julita; Sokolowska, Justyna; Nowak, Zuzanna; Donten, Mikolaj; Celichowski, Grzegorz; Grobelny, Jaroslaw; Krzyzowska, Malgorzata

    2014-01-01

    The interaction between silver nanoparticles and herpesviruses is attracting great interest due to their antiviral activity and possibility to use as microbicides for oral and anogenital herpes. In this work, we demonstrate that tannic acid modified silver nanoparticles sized 13 nm, 33 nm and 46 nm are capable of reducing HSV-2 infectivity both in vitro and in vivo. The antiviral activity of tannic acid modified silver nanoparticles was size-related, required direct interaction and blocked virus attachment, penetration and further spread. All tested tannic acid modified silver nanoparticles reduced both infection and inflammatory reaction in the mouse model of HSV-2 infection when used at infection or for a post-infection treatment. Smaller-sized nanoparticles induced production of cytokines and chemokines important for anti-viral response. The corresponding control buffers with tannic acid showed inferior antiviral effects in vitro and were ineffective in blocking in vivo infection. Our results show that tannic acid modified silver nanoparticles are good candidates for microbicides used in treatment of herpesvirus infections.

  1. Imparting Catalytic Activity to a Covalent Organic Framework Material by Nanoparticle Encapsulation.

    PubMed

    Shi, Xiaofei; Yao, Youjin; Xu, Yulong; Liu, Kun; Zhu, Guangshan; Chi, Lifeng; Lu, Guang

    2017-03-01

    Integrating covalent organic frameworks (COFs) with other functional materials is a useful route to enhancing their performances and extending their applications. We report herein a simple encapsulation method for incorporating catalytically active Au nanoparticles with different sizes, shapes, and contents in a two-dimensional (2D) COF material constructed by condensing 1,3,5-tris(4-aminophenyl)benzene (TAPB) with 2,5-dimethoxyterephthaldehyde (DMTP). The encapsulation is assisted by the surface functionalization of Au nanoparticles with polyvinylpyrrolidone (PVP) and follows a mechanism based on the adsorption of nanoparticles onto surfaces of the initially formed polymeric precursor of COF. The incorporation of nanoparticles does not alter obviously the crystallinity, thermal stability, and pore structures of the framework matrices. The obtained COF composites with embedded but accessible Au nanoparticles possess large surface areas and highly open mesopores and display recyclable catalytic performance for reduction of 4-nitrophenol, which cannot be catalyzed by the pure COF material, with activities relevant to contents and geometric structures of the incorporated nanoparticles.

  2. Anticancer Activity of Nanoparticles Based on PLGA and its Co-polymer: In-vitro Evaluation

    PubMed Central

    Amjadi, Issa; Rabiee, Mohammad; Hosseini, Motahare-Sadat

    2013-01-01

    Attempts have been made to prepare nanoparticles based on poly(lactic-co-glycolic acid) (PLGA) and doxorubicin. Biological evaluation and physio-chemical characterizations were performed to elucidate the effects of initial drug loading and polymer composition on nanoparticle properties and its antitumor activity. PLGA nanoparticles were formulated by sonication method. Lactide/glycolide ratio and doxorubicin amounts have been tailored. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were employed to identify the presence of doxorubicin within nanospheres. The in vitro release studies were performed to determine the initial ant net release rates over 24 h and 20 days, respectively. Furthermore, cytotoxicity assay was measured to evaluate therapeutic potency of doxorubicin-loaded nanoparticles. Spectroscopy and thermal results showed that doxorubicin was loaded into the particles successfully. It was observed that lactide/glycolide content of PLGA nanoparticles containing doxorubicin has more prominent role in tuning particle characteristics. Doxorubicin release profiles from PLGA 75 nanospheres demonstrated that the cumulative release rate increased slightly and higher initial burst was detected in comparison to PLGA 50 nanoparticles. MTT data revealed doxorubicin induced antitumor activity was enhanced by encapsulation process, and increasing drug loading and glycolide portion. The results led to the conclusion that by controlling the drug loading and the polymer hydrophilicity, we can adjust the drug targeting and blood clearance, which may play a more prominent role for application in chemotherapy. PMID:24523742

  3. Tannic Acid Modified Silver Nanoparticles Show Antiviral Activity in Herpes Simplex Virus Type 2 Infection

    PubMed Central

    Orlowski, Piotr; Tomaszewska, Emilia; Gniadek, Marianna; Baska, Piotr; Nowakowska, Julita; Sokolowska, Justyna; Nowak, Zuzanna; Donten, Mikolaj; Celichowski, Grzegorz; Grobelny, Jaroslaw; Krzyzowska, Malgorzata

    2014-01-01

    The interaction between silver nanoparticles and herpesviruses is attracting great interest due to their antiviral activity and possibility to use as microbicides for oral and anogenital herpes. In this work, we demonstrate that tannic acid modified silver nanoparticles sized 13 nm, 33 nm and 46 nm are capable of reducing HSV-2 infectivity both in vitro and in vivo. The antiviral activity of tannic acid modified silver nanoparticles was size-related, required direct interaction and blocked virus attachment, penetration and further spread. All tested tannic acid modified silver nanoparticles reduced both infection and inflammatory reaction in the mouse model of HSV-2 infection when used at infection or for a post-infection treatment. Smaller-sized nanoparticles induced production of cytokines and chemokines important for anti-viral response. The corresponding control buffers with tannic acid showed inferior antiviral effects in vitro and were ineffective in blocking in vivo infection. Our results show that tannic acid modified silver nanoparticles are good candidates for microbicides used in treatment of herpesvirus infections. PMID:25117537

  4. Toxicity and biodistribution of activated and non-activated intravenous iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Tate, J. A.; Ogden, J. A.; Strawbridge, R. R.; Pierce, Z. E.; Hoopes, P. J.

    2009-02-01

    The use of nanoparticles in medical treatment has prompted the question of their safety. In this study, the pathophysiology and biodistribution of three different concentrations of intravenously-delivered dextran-coated Fe3O4 iron oxide nanoparticles (IONP) were evaluated in mice. Some groups of mice were exposed to an AC magnetic field (AMF) at levels comparable with those proposed for cancer treatments. Iron biodistribution analysis for both AMF and non-AMF treated mice was performed for all three concentrations used (.6 mg Fe/mouse, 1.8 mg Fe/mouse, and 5.6 mg Fe/mouse). Blood urea nitrogen, alanine transaminase, alkaline phosphatase, total serum protein, and creatinine were also assessed at 4 hours, 7 days, and 14 days post-injection. Histological analysis of lung, spleen, heart, liver, and kidney tissue was conducted at 7 and 14 days post-injection. Prussian blue and H&E stains were used to histomorphometrically assess iron content in the tissues studied. Preliminary results demonstrate small temporary elevation in liver enzymes and hepatocyte vacuolization at all iron concentrations studied. Liver and spleen were the primary sites of IONP deposition. None of the animals demonstrated systemic or local toxicity or illness, with or without AMF activation.

  5. Photochemical preparation of CdS hollow microspheres at room temperature and their use in visible-light photocatalysis

    NASA Astrophysics Data System (ADS)

    Huang, Yuying; Sun, Fengqiang; Wu, Tianxing; Wu, Qingsong; Huang, Zhong; Su, Heng; Zhang, Zihe

    2011-03-01

    CdS hollow microspheres have been successfully prepared by a photochemical preparation technology at room temperature, using polystyrene latex particles as templates, CdSO 4 as cadmium source and Na 2S 2O 3 as both sulphur source and photo-initiator. The process involved the deposition of CdS nanoparticles on the surface of polystyrene latex particles under the irradiation of an 8 W UV lamp and the subsequent removal of the latex particles by dispersing in dichloromethane. Photochemical reactions at the sphere/solution interface should be responsible for the formation of hollow spheres. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Such hollow spheres could be used in photocatalysis and showed high photocatalytic activities in photodegradation of methyl blue (MB) in the presence of H 2O 2. The method is green, simple, universal and can be extended to prepare other sulphide and oxide hollow spheres.

  6. Gold nanoparticles supported in zirconia-ceria mesoporous thin films: a highly active reusable heterogeneous nanocatalyst.

    PubMed

    Violi, Ianina L; Zelcer, Andrés; Bruno, Mariano M; Luca, Vittorio; Soler-Illia, Galo J A A

    2015-01-21

    Gold nanoparticles (NP) trapped in the mesopores of mixed zirconia-ceria thin films are prepared in a straightforward and reproducible way. The films exhibit enhanced stability and excellent catalytic activity in nitro-group reduction by borohydride and electrocatalytic activity in CO and ethanol oxidation and oxygen reduction.

  7. Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against E. coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achievin...

  8. Evaluation of antibacterial activity of plant mediated CaO nanoparticles using Cissus quadrangularis extract.

    PubMed

    Marquis, Gowdhami; Ramasamy, Balagurunathan; Banwarilal, Sarkar; Munusamy, Ayyasamy Pudukadu

    2016-02-01

    An assessment of antibacterial activity of greenly synthesized nanoparticles using aqueous stem extract of Cissus quadrangularis was carried out. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, SEM, XRD, FTIR and further subjected for antibacterial activity against the pathogens Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae and Vibrio cholerae. The SEM photograph represents cubic and hexagonal shape of NPs about 58nm respectively whereas the XRD indicated the pure phase of the product and no impurity in peaks of well crystallized products. The FTIR spectrum of nanoparticles showed intensive peaks with blue shift indicating the crystalline and shorten the distance of crystal lattice. The plant mediated CaO nanoparticles showed maximum inhibition on E. coli followed by other strains. In MIC, the plant mediated CaO NPs possess high activity against all the test organisms whereas the CaCl2 and CaO compounds were moderately active. The approach to the synthesis of plant mediated CaO NPs has many advantages as scaled up, economic viability, etc. Application of such ecofriendly nanoparticles in bactericidal, wound healing and other medical applications makes this method potential existing for the large scale synthesis of the inorganic materials.

  9. Enhanced catalytic activity of solid and hollow platinum-cobalt nanoparticles towards reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Krajczewski, Jan; Kołątaj, Karol; Kudelski, Andrzej

    2016-12-01

    Previous investigations of hollow platinum nanoparticles have shown that such nanostructures are more active catalysts than their solid counterparts towards the following electrochemical reactions: reduction of oxygen, evolution of hydrogen, and oxidation of borohydride, methanol and formic acid. In this work we show that synthesised using standard galvanic replacement reaction (with Co templates) hollow platinum nanoparticles exhibit enhanced catalytic activity also towards reduction of 4-nitrophenol by sodium borohydride in water. Unlike in the case of procedures involving hollow platinum catalysts employed so far to carry out this reaction it is not necessary to couple analysed platinum nanoparticles to the surface of an electrode. Simplification of the analyzed reaction may eliminate same experimental errors. We found that the enhanced catalytic activity of hollow Pt nanoparticles is not only connected with generally observed larger surface area of hollow nanostructures, but is also due to the contamination of formed hollow nanostructures with cobalt, from which sacrificial templates used in the synthesis of hollow Pt nanostrustures have been formed. Because using sacrificial templates is a typical method of synthesis of hollow metal nanostructures, formed hollow nanoparticles are probably often contaminated, which may significantly influence their catalytic activity.

  10. Evaluation of the antibacterial activity of poly-( d, l-lactide-co-glycolide) nanoparticles containing violacein

    NASA Astrophysics Data System (ADS)

    Martins, D.; Costa, F. T. M.; Brocchi, M.; Durán, N.

    2011-01-01

    Since violacein—an antibiotic, antiviral, and antiparasitic compound—exhibits poor solubility in water, polymeric poly-( d, l-lactide-co-glycolide) nanoparticles containing this compound improved its solubility and biological activity. The nanoparticles were prepared by the nanoprecipitation method and characterized in terms of average diameter, zeta potential, drug loading, polymer recovery, in vitro release kinetic, and in vitro antibacterial activity. Nanoparticles with diameters between 116 and 139 nm and negative-charged outer surfaces were obtained. Drug-loading efficiency and polymer recovery were 87 and 93%, respectively. In vitro release kinetics assays showed that violacein loaded in these nanoparticles has sustained release behavior until 5 days. Both free and nanoparticles-loaded violacein exhibited in vitro antibacterial activity against Staphylococcus aureus ATCC 29213 and ATCC 25923 strains and exhibiting around two to five times lower minimum inhibitory concentration (MIC) than free violacein, respectively. The encapsulated violacein was efficient against methicilin-resistant Staphylococcus aureus (MRSA) strains. No significant activity against Escherichia coli and Salmonella enterica was found.

  11. A novel green synthesis of silver nanoparticles using soluble starch and its antibacterial activity.

    PubMed

    Yakout, Sobhy M; Mostafa, Ashraf A

    2015-01-01

    A green method of Silver nanoparticles (AgNPs) preparation has been established. This method depends on reduction of silver nitrate with soluble starch. The formation of AgNPs was observed by the color change from colorless to dark brown through the starch addition into silver nitrate solution. It was observed that use of starch makes convenient method for the synthesis of silver nanoparticles and can reduce silver ions into the produced silver nanoparticles within one hour of reaction time without using any harsh conditions. The prepared silver nanoparticles were characterized by using UV-visible spectroscopy and evaluated for its antimicrobial activity. The synthesized green AgNPs showed a potential antibacterial activity that was stronger against Gram positive pathogenic bacteria (Staphylococus aureus and Streptococus pyogenes) than against Gram negative pathogenic bacteria (Salmonella typhi, Shigellasonnei and Pseudomonas aeruginosa). Inhibition zones diameter of antibacterial activity depends upon nanoparticles concentration as AgNPs exhibited greater inhibition zone for S.aureus (16.4 mm) followed by P. aeruginosa and S. pyogenes while the least activity was observed for S. typhi (10.4 mm) at 40 μl/ disc. These results suggested that AgNPs can be used as an effective antiseptic agents in medical fields and process of synthesis creates new opportunities in process development for the synthesis of safe and eco-friendly AgNPs.

  12. A novel green synthesis of silver nanoparticles using soluble starch and its antibacterial activity

    PubMed Central

    Yakout, Sobhy M; Mostafa, Ashraf A

    2015-01-01

    A green method of Silver nanoparticles (AgNPs) preparation has been established. This method depends on reduction of silver nitrate with soluble starch. The formation of AgNPs was observed by the color change from colorless to dark brown through the starch addition into silver nitrate solution. It was observed that use of starch makes convenient method for the synthesis of silver nanoparticles and can reduce silver ions into the produced silver nanoparticles within one hour of reaction time without using any harsh conditions. The prepared silver nanoparticles were characterized by using UV-visible spectroscopy and evaluated for its antimicrobial activity. The synthesized green AgNPs showed a potential antibacterial activity that was stronger against Gram positive pathogenic bacteria (Staphylococus aureus and Streptococus pyogenes) than against Gram negative pathogenic bacteria (Salmonella typhi, Shigellasonnei and Pseudomonas aeruginosa). Inhibition zones diameter of antibacterial activity depends upon nanoparticles concentration as AgNPs exhibited greater inhibition zone for S.aureus (16.4 mm) followed by P. aeruginosa and S. pyogenes while the least activity was observed for S. typhi (10.4 mm) at 40 μl/ disc. These results suggested that AgNPs can be used as an effective antiseptic agents in medical fields and process of synthesis creates new opportunities in process development for the synthesis of safe and eco-friendly AgNPs. PMID:26064246

  13. A highly active Pd-P nanoparticle electrocatalyst for enhanced formic acid oxidation synthesized via stepwise electroless deposition.

    PubMed

    Poon, Kee Chun; Khezri, Bahareh; Li, Yao; Webster, Richard D; Su, Haibin; Sato, Hirotaka

    2016-02-28

    A highly active Pd-P nanoparticle electrocatalyst for formic acid oxidation was synthesized using NaH2PO2 as the reducing agent. The Pd-P nanoparticles were amorphous and exhibited higher specific and mass activity values compared to commercial Pd/C electrocatalyts and reported literature values. Furthermore, the Pd-P nanoparticles were found to be more durable than Pd/C electrocatalyts.

  14. Effect of laser irradiation of nanoparticles in aqueous uranium salt solutions on nuclide activity

    SciTech Connect

    Simakin, Aleksandr V; Shafeev, Georgii A

    2011-07-31

    This paper presents an experimental study of the effect of laser irradiation of aqueous uranyl chloride solutions containing gold nanoparticles on the activity of the uranium series radionuclides {sup 234}Th, {sup 234m}Pa, and {sup 235}U. The solutions were exposed to femtosecond Ti:sapphire laser pulses and to the second or third harmonic of a Nd:YAG laser (150-ps pulses) at a peak intensity in the medium of {approx}10{sup 12} W cm{sup -2}. The activities of the radionuclides in the irradiated solutions were shown to differ markedly from their equilibrium values. The sign of the deviation depends on the laser wavelength. The measured activity deviations can be interpreted as evidence that laser exposure of nanoparticles accelerates the alpha and beta decays of the radionuclides. The observed effects are accounted for in terms of a mechanism that involves resonant enhancement of optical waves by metallic nanoparticles. (interaction of laser radiation with matter)

  15. Preparation of gold nanoparticles using Salicornia brachiata plant extract and evaluation of catalytic and antibacterial activity

    NASA Astrophysics Data System (ADS)

    Ayaz Ahmed, Khan Behlol; Subramanian, Swetha; Sivasubramanian, Aravind; Veerappan, Ganapathy; Veerappan, Anbazhagan

    2014-09-01

    The current study deals with the synthesis of gold nanoparticles (AuNPs) using Salicornia brachiata (Sb) and evaluation of their antibacterial and catalytic activity. The SbAuNPs showed purple color with a characteristic surface plasmon resonance peak at 532 nm. Scanning electron microscopy and transmission electron microscopy revealed polydispersed AuNPs with the size range from 22 to 35 nm. Energy dispersive X-ray and thin layer X-ray diffraction analysis clearly shows that SbAuNPs was pure and crystalline in nature. As prepared gold nanoparticles was used as a catalyst for the sodium borohydride reduction of 4-nitro phenol to 4-amino phenol and methylene blue to leucomethylene blue. The green synthesized nanoparticles exhibited potent antibacterial activity against the pathogenic bacteria, as evidenced by their zone of inhibition. In addition, we showed that the SbAuNPs in combination with the regular antibiotic, ofloxacin, exhibit superior antibacterial activity than the individual.

  16. Enhanced Antimicrobial Activity Of Antibiotics Mixed With Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep; Kumar, Neeraj; Bhanjana, Gaurav; Thakur, Rajesh; Dilbaghi, Neeraj

    2011-12-01

    Current producers of antimicrobial technology have a long lasting, environmentally safe, non-leaching, water soluble solution that will eventually replace all poisons and heavy metals. The transition metal ions inevitably exist as metal complexes in biological systems by interaction with the numerous molecules possessing groupings capable of complexation or chelation. Nanoparticles of metal oxides offer a wide variety of potential applications in medicine due to the unprecedented advances in nanobiotechnology research. the bacterial action of antibiotics like penicillin, erythryomycin, ampicillin, streptomycin, kanamycin etc. and that of a mixture of antibiotics and metal and metal oxide nanoparticles like zinc oxide, zirconium, silver and gold on microbes was examined by the agar-well-diffusion method, enumeration of colony-forming units (CFU) and turbidimetry.

  17. Emerging concepts of laser-activated nanoparticles for tissue bonding

    NASA Astrophysics Data System (ADS)

    Matteini, Paolo; Ratto, Fulvio; Rossi, Francesca; Pini, Roberto

    2012-01-01

    We report recent achievements and future perspectives of minimally invasive bonding of biological tissues triggered by laser light. In particular, we review new advancements in the biomedical exploitation of near-infrared absorbing gold nanoparticles as an original solution for the photothermal closure of surgical incisions. Advanced concepts of laser tissue bonding involving the application of hybrid nanocomposites obtained by inclusion of nanochromophores into biopolymer scaffolds are also introduced. The perspectives of tissue bonding are discussed in the following aspects: (1) tissue bonding with highly-stabilized nanochromophores, (2) enhanced tissue bonding with patterned nanocomposites, (3) real-time monitoring of temperature distributions, (4) tracking of tissue regeneration based on the optical resonances of gold nanoparticles.

  18. Photochemical mechanisms of light-triggered release from nanocarriers

    PubMed Central

    Fomina, Nadezda; Sankaranarayanan, Jagadis; Almutairi, Adah

    2012-01-01

    Over the last three decades, a handful of photochemical mechanisms have been applied to a large number of nanoscale assemblies that encapsulate a payload to afford spatio-temporal and remote control over activity of the encapsulated payload. Many of these systems are designed with an eye towards biomedical applications, as spatio-temporal and remote control of bioactivity would advance research and clinical practice. This review covers five underlying photochemical mechanisms that govern the activity of the majority of photoresponsive nanocarriers: 1. photo driven isomerization and oxidation, 2. surface plasmon absorption and photothermal effects, 3. photo driven hydrophobicity changes, 4. photo driven polymer backbone fragmentation and 5. photo driven de-crosslinking. The ways in which these mechanisms have been incorporated into nanocarriers and how they affect release is detailed, as well as the advantages and disadvantages of each system. PMID:22386560

  19. Relationship between the size of nanoparticles and their adjuvant activity: Data from a study with an improved experimental design

    PubMed Central

    Li, Xinran; Sloat, Brian R.; Yanasarn, Nijaporn; Cui, Zhengrong

    2011-01-01

    There is a growing interest in identifying the relationship between the size of nanoparticles and their adjuvant activity, but the results from recent studies remain controversial. To address the controversy, it was thought that one should pay attention to the nanoparticle formulations to make sure that the antigen-loaded nanoparticles to be compared are not only different in particle size, but more importantly, as identical to each other as possible in all other formulation properties. In the present study, using ovalbumin (OVA) as a model antigen conjugated onto nanoparticles engineered from lecithin/glyceryl monostearate-in-water emulsions, we prepared OVA-nanoparticles of 230 nm and 708 nm. Before evaluating the immune responses induced by them in a mouse model, we made sure that: i) the sizes of the two OVA-nanoparticles did not extensively overlap, ii) the nanoparticles have similar zeta potentials and comparable antigen-loading, and iii) the nanoparticles did not aggregate when suspended in simulated biological media. We then showed that when subcutaneously injected into mice, the 230 nm OVA-conjugated nanoparticles induced stronger OVA-specific antibody and cellular immune responses than the 708 nm OVA-nanoparticles. Future studies attempting to correlate the size of nanoparticles and their adjuvant activities need to consider formulation parameters to ensure that the particles are different only in size and are stable before and after injection. PMID:21182941

  20. Physicochemical properties, cytotoxicity, and antimicrobial activity of sulphated zirconia nanoparticles

    PubMed Central

    Mftah, Ae; Alhassan, Fatah H; Al-Qubaisi, Mothanna Sadiq; El Zowalaty, Mohamed Ezzat; Webster, Thomas J; Sh-eldin, Mohammed; Rasedee, Abdullah; Taufiq-Yap, Yun Hin; Rashid, Shah Samiur

    2015-01-01

    Nanoparticle sulphated zirconia with Brønsted acidic sites were prepared here by an impregnation reaction followed by calcination at 600°C for 3 hours. The characterization was completed using X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared spectroscopy, Brunner-Emmett-Teller surface area measurements, scanning electron microscopy with energy dispersive X-ray spectroscopy, and transmission electron microscopy. Moreover, the anticancer and antimicrobial effects were investigated for the first time. This study showed for the first time that the exposure of cancer cells to sulphated zirconia nanoparticles (3.9–1,000 μg/mL for 24 hours) resulted in a dose-dependent inhibition of cell growth, as determined by (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Similar promising results were observed for reducing bacteria functions. In this manner, this study demonstrated that sulphated zirconia nanoparticles with Brønsted acidic sites should be further studied for a wide range of anticancer and antibacterial applications. PMID:25632233

  1. Catechin-capped gold nanoparticles: green synthesis, characterization, and catalytic activity toward 4-nitrophenol reduction

    NASA Astrophysics Data System (ADS)

    Choi, Yoonho; Choi, Myung-Jin; Cha, Song-Hyun; Kim, Yeong Shik; Cho, Seonho; Park, Youmie

    2014-03-01

    An eco-friendly approach is described for the green synthesis of gold nanoparticles using catechin as a reducing and capping agent. The reaction occurred at room temperature within 1 h without the use of any external energy and an excellent yield (99%) was obtained, as determined by inductively coupled plasma mass spectrometry. Various shapes of gold nanoparticles with an estimated diameter of 16.6 nm were green-synthesized. Notably, the capping of freshly synthesized gold nanoparticles by catechin was clearly visualized with the aid of microscopic techniques, including high-resolution transmission electron microscopy, atomic force microscopy, and field emission scanning electron microscopy. Strong peaks in the X-ray diffraction pattern of the as-prepared gold nanoparticles confirmed their crystalline nature. The catalytic activity of the as-prepared gold nanoparticles was observed in the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. The results suggest that the newly prepared gold nanoparticles have potential uses in catalysis.

  2. Magnetic field activated lipid–polymer hybrid nanoparticles for stimuli-responsive drug release

    PubMed Central

    Kong, Seong Deok; Sartor, Marta; Hu, Che-Ming Jack; Zhang, Weizhou; Zhang, Liangfang; Jin, Sungho

    2014-01-01

    Stimuli-responsive nanoparticles (SRNPs) offer the potential of enhancing the therapeutic efficacy and minimizing the side-effects of chemotherapeutics by controllably releasing the encapsulated drug at the target site. Currently controlled drug release through external activation remains a major challenge during the delivery of therapeutic agents. Here we report a lipid–polymer hybrid nanoparticle system containing magnetic beads for stimuli-responsive drug release using a remote radio frequency (RF) magnetic field. These hybrid nanoparticles show long-term stability in terms of particle size and polydispersity index in phosphate-buffered saline (PBS). Controllable loading of camptothecin (CPT) and Fe3O4 in the hybrid nanoparticles was demonstrated. RF-controlled drug release from these nanoparticles was observed. In addition, cellular uptake of the SRNPs into MT2 mouse breast cancer cells was examined. Using CPT as a model anticancer drug the nanoparticles showed a significant reduction in MT2 mouse breast cancer cell growth in vitro in the presence of a remote RF field. The ease of preparation, stability, and controllable drug release are the strengths of the platform and provide the opportunity to improve cancer chemotherapy. PMID:23149252

  3. Study of antibacterial activity of Ag and Ag2CO3 nanoparticles stabilized over montmorillonite

    NASA Astrophysics Data System (ADS)

    Sohrabnezhad, Sh.; Pourahmad, A.; Mehdipour Moghaddam, M. J.; Sadeghi, A.

    2015-02-01

    Silver carbonate and silver nanoparticles (NPs) over of stabilizer montmorillonite (MMT) have been synthesized in aqueous and polyol solvent, respectively. Dispersions of silver nanoparticles have been prepared by the reduction of silver nitrate over of MMT in presence and absence of Na2CO3 compound in ethylene glycol. It was observed that montmorillonite was capable of stabilizing formed Ag nanoparticles through the reduction of Ag+ ions in ethylene glycol. Na2CO3 was used as carbonate source in synthesis of Ag2CO3 NPs in water solvent and also for controlling of Ag nanoparticles size in ethylene glycol medium. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (DRS). The TEM images showed that Ag NPs size in presence Na2CO3 salts was smaller than without that. The results indicated intercalation of Ag and Ag2CO3 nanoparticles into the montmorillonite clay layers. The diffuse reflectance spectra exhibited a strong surface plasmon resonance (SPR) adsorption peak in the visible region, resulting from Ag nanoparticles. The antibacterial testing results showed that the Ag2CO3-MMT nanocomposite exhibited an antibacterial activity higher than Ag-MMT sample against Escherichia coli.

  4. Peptide-Directed Assembly of Single-Helical Gold Nanoparticle Superstructures Exhibiting Intense Chiroptical Activity.

    PubMed

    Merg, Andrea D; Boatz, Jennifer C; Mandal, Abhishek; Zhao, Gongpu; Mokashi-Punekar, Soumitra; Liu, Chong; Wang, Xianting; Zhang, Peijun; van der Wel, Patrick C A; Rosi, Nathaniel L

    2016-10-11

    Chiral nanoparticle assemblies are an interesting class of materials whose chiroptical properties make them attractive for a variety of applications. Here, C18-(PEPAu(M-ox))2 (PEPAu(M-ox) = AYSSGAPPM(ox)PPF) is shown to direct the assembly of single-helical gold nanoparticle superstructures that exhibit exceptionally strong chiroptical activity at the plasmon frequency with absolute g-factor values up to 0.04. Transmission electron microscopy (TEM) and cryogenic electron tomography (cryo-ET) results indicate that the single helices have a periodic pitch of approximately 100 nm and consist of oblong gold nanoparticles. The morphology and assembled structure of C18-(PEPAu(M-ox))2 are studied using TEM, atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD) spectroscopy, X-ray diffraction (XRD), and solid-state nuclear magnetic resonance (ssNMR) spectroscopy. TEM and AFM reveal that C18-(PEPAu(M-ox))2 assembles into linear amyloid-like 1D helical ribbons having structural parameters that correlate to those of the single-helical gold nanoparticle superstructures. FTIR, CD, XRD, and ssNMR indicate the presence of cross-β and polyproline II secondary structures. A molecular assembly model is presented that takes into account all experimental observations and that supports the single-helical nanoparticle assembly architecture. This model provides the basis for the design of future nanoparticle assemblies having programmable structures and properties.

  5. Vancomycin loaded superparamagnetic MnFe2O4 nanoparticles coated with PEGylated chitosan to enhance antibacterial activity.

    PubMed

    Esmaeili, Akbar; Ghobadianpour, Sepideh

    2016-03-30

    Increasing prevalence of antibiotic-resistant and failed-treatment make more investigations to deal with these problems. Hence new therapeutic approaches for effective treatment are necessary. Ferrite superparamagnetic nanoparticles have potentially antibacterial activity. In this study we prepared MnFe2O4 superparamagnetic nanoparticles as core by precipitation method and used chitosan crosslinked by glutaraldehyde as shell, then modified with PEG to increase stability of particles against RES. Chitosan coating not only improves the properties of ferrit nanoparticles but also has antibacterial activity. FT-IR confirmed this surface modification; XRD and SEM were developed to demonstrate particle size approximately 25 nm and characteristics of crystal structure of these nanoparticles. Magnetic properties of nanoparticles were evaluated by VSM. Actual drug loading and releasing were examined by UV-vis spectroscopy method. We employed liquid broth dilution method to assessment antibacterial activity of nanoparticles against microorganisms. Significant antibacterial effect against gram negative bacteria was developed.

  6. Facile method to synthesize dopamine-capped mixed ferrite nanoparticles and their peroxidase-like activity

    NASA Astrophysics Data System (ADS)

    Mumtaz, Shazia; Wang, Li-Sheng; Abdullah, Muhammad; Zajif Hussain, Syed; Iqbal, Zafar; Rotello, Vincent M.; Hussain, Irshad

    2017-03-01

    A facile single-step strategy to prepare stable and water-dispersible dopamine-functionalized ultra-small mixed ferrite nanoparticles MFe2O4-DOPA (where M is a bivalent metal atom i.e. Fe, Co Cu, Mn and Ni) at room temperature is described. The nanoparticles formed have narrow size distribution as indicated by their characterization using transmission electron microscopy (TEM) and dynamic light scattering. The surface chemistry of these nanoparticles was probed by FTIR spectroscopy indicating their successful capping with dopamine ligands, which was further confirmed using zetapotential measurements and thermogravimetric analysis. The comparative horseradish peroxidase (HRP)—like activity of these cationic mixed ferrites nanoparticles was studied at pH 4.6 using a negatively-charged 2, 2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as a chromogenic substrate in the presence of hydrogen peroxide. A time-dependent relative peroxidase-like activity follows the following order CoFe2O4-DOPA  >  MnFe2O4-DOPA  >  CuFe2O4-DOPA  >  NiFe2O4-DOPA  >  Fe3O4-DOPA. This diversity in HRP-like activity may be attributed to the different redox properties of ferrite nanoparticles when doped with M (Fe, Co Cu, Mn and Ni).

  7. The inhibition effect of starch nanoparticles on tyrosinase activity and its mechanism.

    PubMed

    Yang, Jie; Chang, Ranran; Ge, Shengju; Zhao, Mei; Liang, Caifeng; Xiong, Liu; Sun, Qingjie

    2016-12-07

    The objective of the current research was to investigate the effects of starch nanoparticles (SNPs) prepared from waxy maize, potato, normal corn, and tapioca starches on the activity of tyrosinase. As a main polyphenol oxidase, tyrosinase not only induces fruit and vegetable browning but also causes skin diseases by overproducing melanin. Herein, for the first time, we evaluated the inhibitory kinetics of SNPs on tyrosinase. It turned out that SNPs inhibited tyrosinase activity reversibly. The IC50 values of hollow nanoparticles, amylopectin nanoparticles, corn starch nanoparticles, and tapioca starch nanoparticles were 0.308, 0.669, 1.490, and 4.774 μM, respectively. Assay of fluorescence spectra demonstrated that SNPs quenched the tyrosinase intrinsic fluorescence. Moreover, binding constant and binding sites found that SNPs were bound to tyrosinase through van der Waals forces, hydrogen bonds, as well as electrostatic interactions. Analysis of circular dichroism indicated that the incorporation of SNPs into tyrosinase prompted conformational alteration of the enzyme. Furthermore, inhibition of browning by SNPs loading with l-dopa compound indicated that not only the tyrosinase activity was inhibited, but also SNPs decreased free dopa content by adsorption. This research on SNPs as potential inhibitors could give rise to advancement in the realm of anti-tyrosinase and have versatile applications in medicine, food, cosmetics, materials and drugs.

  8. Novel combustion method to prepare octahedral NiO nanoparticles and its photocatalytic activity

    SciTech Connect

    Jegatha Christy, A.; Umadevi, M.

    2013-10-15

    Graphical abstract: - Highlights: • NiO nanoparticles were synthesized by solution combustion method. • Prepared NiO nanoparticles are fcc structure. • Synthesized NiO nanoparticles are octahedral shape. • Shows good photocatalytic activity. - Abstract: Nickel oxide nanoparticles (NiO NPs) were synthesized by solution combustion method using glycine and citric acid as fuels. The X-ray diffraction (XRD) result confirms the face centered cubic (fcc) structure of NiO. The octahedral shape of NiO NPs was confirmed by field emission scanning electron microscope (FESEM) and high resolution transmission electron microscopy (HRTEM). It is possible to suggest that the organic fuel (citric acid/glycine) is responsible for the formation of the octahedral shape due to the easier complex formation. Photocatalytic activity of NiO NPs also evaluated and found that the prepared NiO NPs have high photocatalytic degradation. In the present study, the crystalline nature and shape of the NiO nanoparticles plays a vital role in determining the photocatalytic activity.

  9. In Vitro and in Vivo Demonstration of Photodynamic Activity and Cytoplasm Imaging through TPE Nanoparticles.

    PubMed

    Jayaram, Dhanya T; Ramos-Romero, Sara; Shankar, Balaraman H; Garrido, Cristina; Rubio, Nuria; Sanchez-Cid, Lourdes; Gómez, Salvador Borros; Blanco, Jeronimo; Ramaiah, Danaboyina

    2016-01-15

    We synthesized novel tetraphenylethene (TPE) conjugates, which undergo unique self-assembly to form spherical nanoparticles that exhibited aggregation induced emission (AIE) in the near-infrared region. These nanoparticles showed significant singlet oxygen generation efficiency, negligible dark toxicity, rapid cellular uptake, efficient localization in cytoplasm, and high in vitro photocytotoxicity as well as in vivo photodynamic activity against a human prostate tumor animal model. This study demonstrates, for the first time, the power of the self-assembled AIE active tetraphenylethene conjugates in aqueous media as a nanoplatform for future therapeutic applications.

  10. Generic phosphatase activity detection using zinc mediated aggregation modulation of polypeptide-modified gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Selegård, Robert; Enander, Karin; Aili, Daniel

    2014-11-01

    A challenge in the design of plasmonic nanoparticle-based colorimetric assays is that the change in colloidal stability, which generates the colorimetric response, is often directly linked to the biomolecular recognition event. New assay strategies are hence required for every type of substrate and enzyme of interest. Here, a generic strategy for monitoring of phosphatase activity is presented where substrate recognition is completely decoupled from the nanoparticle stability modulation mechanism, which enables detection of a wide range of enzymes using different natural substrates with a single simple detection scheme. Phosphatase activity generates inorganic phosphate that forms an insoluble complex with Zn2+. In a sample containing a preset concentration of Zn2+, phosphatase activity will markedly reduce the concentration of dissolved Zn2+ from the original value, which in turn affects the aggregation of gold nanoparticles functionalized with a designed Zn2+ responsive polypeptide. The change in nanoparticle stability thus provides a rapid and sensitive readout of the phosphatase activity. The assay is not limited to a particular enzyme or enzyme substrate, which is demonstrated using three completely different phosphatases and five different substrates, and thus constitutes a highly interesting system for drug screening and diagnostics.A challenge in the design of plasmonic nanoparticle-based colorimetric assays is that the change in colloidal stability, which generates the colorimetric response, is often directly linked to the biomolecular recognition event. New assay strategies are hence required for every type of substrate and enzyme of interest. Here, a generic strategy for monitoring of phosphatase activity is presented where substrate recognition is completely decoupled from the nanoparticle stability modulation mechanism, which enables detection of a wide range of enzymes using different natural substrates with a single simple detection scheme

  11. Silver nanoparticle production by the fungus Fusarium oxysporum: nanoparticle characterisation and analysis of antifungal activity against pathogenic yeasts

    PubMed Central

    Ishida, Kelly; Cipriano, Talita Ferreira; Rocha, Gustavo Miranda; Weissmüller, Gilberto; Gomes, Fabio; Miranda, Kildare; Rozental, Sonia

    2013-01-01

    The microbial synthesis of nanoparticles is a green chemistry approach that combines nanotechnology and microbial biotechnology. The aim of this study was to obtain silver nanoparticles (SNPs) using aqueous extract from the filamentous fungus Fusarium oxysporum as an alternative to chemical procedures and to evaluate its antifungal activity. SNPs production increased in a concentration-dependent way up to 1 mM silver nitrate until 30 days of reaction. Monodispersed and spherical SNPs were predominantly produced. After 60 days, it was possible to observe degenerated SNPs with in additional needle morphology. The SNPs showed a high antifungal activity against Candida and Cryptococcus , with minimum inhibitory concentration values ≤ 1.68 µg/mL for both genera. Morphological alterations of Cryptococcus neoformans treated with SNPs were observed such as disruption of the cell wall and cytoplasmic membrane and lost of the cytoplasm content. This work revealed that SNPs can be easily produced by F. oxysporum aqueous extracts and may be a feasible, low-cost, environmentally friendly method for generating stable and uniformly sized SNPs. Finally, we have demonstrated that these SNPs are active against pathogenic fungi, such as Candida and Cryptococcus . PMID:24714966

  12. Silver nanoparticle production by the fungus Fusarium oxysporum: nanoparticle characterisation and analysis of antifungal activity against pathogenic yeasts.

    PubMed

    Ishida, Kelly; Cipriano, Talita Ferreira; Rocha, Gustavo Miranda; Weissmüller, Gilberto; Gomes, Fabio; Miranda, Kildare; Rozental, Sonia

    2014-04-01

    The microbial synthesis of nanoparticles is a green chemistry approach that combines nanotechnology and microbial biotechnology. The aim of this study was to obtain silver nanoparticles (SNPs) using aqueous extract from the filamentous fungus Fusarium oxysporum as an alternative to chemical procedures and to evaluate its antifungal activity. SNPs production increased in a concentration-dependent way up to 1 mM silver nitrate until 30 days of reaction. Monodispersed and spherical SNPs were predominantly produced. After 60 days, it was possible to observe degenerated SNPs with in additional needle morphology. The SNPs showed a high antifungal activity against Candida and Cryptococcus , with minimum inhibitory concentration values ≤ 1.68 µg/mL for both genera. Morphological alterations of Cryptococcus neoformans treated with SNPs were observed such as disruption of the cell wall and cytoplasmic membrane and lost of the cytoplasm content. This work revealed that SNPs can be easily produced by F. oxysporum aqueous extracts and may be a feasible, low-cost, environmentally friendly method for generating stable and uniformly sized SNPs. Finally, we have demonstrated that these SNPs are active against pathogenic fungi, such as Candida and Cryptococcus.

  13. Combination of Silver Nanoparticles and Curcumin Nanoparticles for Enhanced Anti-biofilm Activities.

    PubMed

    Loo, Ching-Yee; Rohanizadeh, Ramin; Young, Paul M; Traini, Daniela; Cavaliere, Rosalia; Whitchurch, Cynthia B; Lee, Wing-Hin

    2016-03-30

    Biofilm tolerance has become a serious clinical concern in the treatment of nosocomial pneumonia owing to the resistance to various antibiotics. There is an urgent need to develop alternative antimicrobial agents or combination drug therapies that are effective via different mechanisms. Silver nanoparticles (AgNPs) have been developed as an anti-biofilm agent for the treatment of infections associated with the use of mechanical ventilations, such as endotracheal intubation. Meanwhile curcumin, a phenolic plant extract, has displayed natural anti-biofilm properties through the inhibition of bacterial quorum sensing systems. The aim of this study was to investigate the possible synergistic/additive interactions of AgNPs and curcumin nanoparticles (Cur-NPs) against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) microorganisms. The combination of AgNPs and Cur-NPs (termed Cur-SNPs) at 100 μg/mL disrupted 50% of established bacterial biofilms (formed on microtiter plates). However, further increase in the concentration of Cur-SNPs failed to effectively eliminate the biofilms. To achieve the same effect, at least 500 μg/mL Cur-NP alone was needed. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) revealed that combination therapy (Cur-SNPs) was the most potent to eradicate preformed biofilm compared to monodrug therapy. These agents are also nontoxic to healthy human bronchial epithelial cells (BEAS2B).

  14. Biogenic copper oxide nanoparticles synthesis using Tabernaemontana divaricate leaf extract and its antibacterial activity against urinary tract pathogen

    NASA Astrophysics Data System (ADS)

    Sivaraj, Rajeshwari; Rahman, Pattanathu K. S. M.; Rajiv, P.; Salam, Hasna Abdul; Venckatesh, R.

    2014-12-01

    This investigation explains the biosynthesis and characterization of copper oxide nanoparticles from an Indian medicinal plant by an eco-friendly method. The main objective of this study is to synthesize copper oxide nanoparticles from Tabernaemontana divaricate leaves through a green chemistry approach. Highly stable, spherical copper oxide nanoparticles were synthesized by using 50% concentration of Tabernaemontana leaf extract. Formation of copper oxide nanoparticles have been characterized by UV-Vis absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM) analysis. All the analyses revealed that copper oxide nanoparticles were 48 ± 4 nm in size. Functional groups and chemical composition of copper oxide were also confirmed. Antimicrobial activity of biogenic copper oxide nanoparticles were investigated and maximum zone of inhibition was found in 50 μg/ml copper oxide nanoparticles against urinary tract pathogen (Escherichia coli).

  15. Antibacterial activity of silver nanoparticles with different morphologies as well as their possible antibacterial mechanism

    NASA Astrophysics Data System (ADS)

    Hu, Guansong; Jin, Wenxiu; Chen, Qingyuan; Cai, Yuchun; Zhu, Qiuhua; Zhang, Wanzhong

    2016-10-01

    Silver nanoparticles (AgNPs) have good antibacterial activity and their morphologies have important influence on their activity. The relationship between their bactericidal property and morphology has not been studied thoroughly. Silver triangular nanoplates have basic {111} surface, nanospheres and nanocubes mainly have {100} planes, and nanorods have {100} side surfaces and {111} end facets. It was said that {111} crystal plane of AgNPs may play a prime role in antibacterial progress. Moreover, the antibacterial activity of nanocubes is not very clear when compared to nanoparticles with other morphologies. In this paper, we studied the antibacterial activity of nanocubes and attempted to confirm whether nanoparticles with {111} crystal facet truly had stronger antibacterial activity than other nanoparticles. We prepared four kinds of AgNPs and found silver triangle nanoplates had the best antibacterial activity, while nanospheres, nanocubes and short nanorods showed similar efficacy. It may provide a reference for safe application of AgNPs with different morphologies in the medical field.

  16. Uniformly dispersed CdS nanoparticles sensitized TiO{sub 2} nanotube arrays with enhanced visible-light photocatalytic activity and stability

    SciTech Connect

    Liu, Lingjuan; Lv, Jun; Xu, Guangqing; Wang, Yan; Xie, Kui; Chen, Zhong; Wu, Yucheng

    2013-12-15

    In this study, TiO{sub 2} nanotube arrays (TiO{sub 2}-NTs) with various intertube spaces were fabricated in the electrolyte with different water contents and the CdS nanoparticles (CdS NPs) were further deposited onto the TiO{sub 2}-NTs as a sensitizer via a sequential chemical bath deposition (S-CBD) method. The FE-SEM, TEM, XRD and XPS results demonstrated that the CdS NPs were uniformly deposited onto the surface of TiO{sub 2}-NTs. It was found that higher water content in electrolyte was in favor of large intertube space and pore size and the uniform deposition of CdS NPs. The photocatalytic degradation of methyl orange was tested with the as-prepared CdS/TiO{sub 2}-NTs under visible light (λ>400 nm). It was found that the photodegradation rate reached as high as 96.7% under visible irradiation for 180 min. In addition, a reasonable degradation rate of 75.8% was achieved even after 5 cycles, suggesting a good photocatalytic stability of the as-prepared CdS/TiO{sub 2}-NTs. - Graphical abstract: The whole sheet of CdS NPs sensitized TiO{sub 2}-NTs with the Ti subtract was used for degradation of methyl orange under visible light (λ>400 nm) on a XPA-7 photochemical reactor. - Highlights: • Intertube space, pore size were controlled by changing water content in electrolyte. • CdS nanoparticles were uniformly deposited onto the surface of TiO{sub 2} nanotubes. • The catalyst with Ti substrate used as a whole was very convenient for recycling. • Visible-light photocatalytic activity and stability were highly enhanced.

  17. Light-driven transformation processes of anisotropic silver nanoparticles.

    PubMed

    Lee, George P; Shi, Yichao; Lavoie, Ellen; Daeneke, Torben; Reineck, Philipp; Cappel, Ute B; Huang, David M; Bach, Udo

    2013-07-23

    The photoinduced formation of silver nanoprisms from smaller silver seed particles in the presence of citrate anions is a classic example of a photomorphic reaction. In this case, light is used as a convenient tool to dynamically manipulate the shape of metal nanoparticles. To date, very little is known about the prevailing reaction mechanism of this type of photoreaction. Here we provide a detailed study of the shape transformation dynamics as a function of a range of different process parameters, such as photon energy and photon flux. For the first time, we provide direct evidence that the photochemical synthesis of silver nanoprisms from spherical seed nanoparticles proceeds via a light-activated two-dimensional coalescence mechanism. On the other hand, we could show that Ostwald ripening becomes the dominant reaction mechanism when larger silver nanoprisms are grown from photochemically synthesized smaller nanoprisms. This two-step reaction proceeds significantly faster and yields more uniform, sharper nanoprisms than the classical one-step photodevelopment process from seeds. The ability to dynamically control nanoparticle shapes and properties with light opens up novel synthesis avenues but also, more importantly, allows one to conceive new applications that exploit the nonstatic character of these nanoparticles and the ability to control and adjust their properties at will in a highly dynamic fashion.

  18. Visible-light photochemical activity of heterostructured core-shell materials composed of selected ternary titanates and ferrites coated by tiO2.

    PubMed

    Li, Li; Liu, Xuan; Zhang, Yiling; Nuhfer, Noel T; Barmak, Katayun; Salvador, Paul A; Rohrer, Gregory S

    2013-06-12

    Heterostructured photocatalysts comprised of microcrystalline (mc-) cores and nanostructured (ns-) shells were prepared by the sol-gel method. The ability of titania-coated ATiO3 (A = Fe, Pb) and AFeO3 (A = Bi, La, Y) catalysts to degrade methylene blue in visible light (λ > 420 nm) was compared. The catalysts with the titanate cores had enhanced photocatalytic activities for methylene blue degradation compared to their components alone, whereas the catalysts with ferrite cores did not. The temperature at which the ns-titania shell is crystallized influences the photocatalytic dye degradation. mc-FeTiO3/ns-TiO2 annealed at 500 °C shows the highest reaction rate. Fe-doped TiO2, which absorbs visible light, did not show enhanced photocatalytic activity for methylene blue degradation. This result indicates that iron contamination is not a decisive factor in the reduced reactivity of the titania coated ferrite catalysts. The higher reactivity of materials with the titanate cores suggests that photogenerated charge carriers are more easily transported across the titanate-titanate interface than the ferrite-titanate interface and this provides guidance for materials selection in composite catalyst design.

  19. Synthesis of supported bimetallic nanoparticles with controlled size and composition distributions for active site elucidation

    SciTech Connect

    Hakim, Sikander H.; Sener, Canan; Alba Rubio, Ana C.; Gostanian, Thomas M.; O'neill, Brandon J; Ribeiro, Fabio H.; Miller, Jeffrey T.; Dumesic, James A

    2015-08-01

    Elucidation of active sites in supported bimetallic catalysts is complicated by the high level of dispersity in the nanoparticle size and composition that is inherent in conventional methods of catalyst preparation. We present a synthesis strategy that leads to highly dispersed, bimetallic nanoparticles with uniform particle size and composition by means of controlled surface reactions. We demonstrate the synthesis of three systems, RhMo, PtMo, and RhRe, consisting of a highly reducible metal with an oxophilic promoter. These catalysts are characterized by FTIR, CO chemisorption, STEM/EDS, TPR, and XAS analysis. The catalytic properties of these bimetallic nanoparticles were probed for the selective CO hydrogenolysis of (hydroxymethyl)tetrahydropyran to produce 1,6 hexanediol. Based on the characterization results and reactivity trends, the active sites in the hydrogenolysis reaction are identified to be small ensembles of the more noble metal (Rh, Pt) adjacent to highly reduced moieties of the more oxophilic metal (Mo, Re).

  20. Biocompatibility and antibacterial activity of the Adathoda vasica Linn extract mediated silver nanoparticles.

    PubMed

    Latha, M; Priyanka, M; Rajasekar, P; Manikandan, R; Prabhu, N M

    2016-04-01

    The aim of this study is to investigate the biocompatibility and anti-Vibrio efficacy of green synthesized silver nanoparticles (AgNPs) using an aqueous leaf extract of Adathoda vasica (A. vasica). The green synthesized silver nanoparticles were characterized by UV-vis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). A. vasica AgNPs showed significant antibacterial activity against Vibrio parahaemolyticus in agar bioassay and well diffusion method. Further, nanoparticles interactions with bacteria and its antibacterial activity were confirmed by CLSM analysis. In vivo evaluation results confirmed that synthesized A. vasica AgNPs had good antibacterial efficacy and also nontoxic to the Artemia nauplii.

  1. Tunable luminescence and enhanced photocatalytic activity for Eu(III) doped Bi2WO6 nanoparticles.

    PubMed

    Gu, Haidong; Yu, Lei; Wang, Juan; Ni, Min; Liu, Tingting; Chen, Feng

    2017-04-15

    A series of Eu(III) doped Bi2WO6 nanoparticles were synthesized by a hydrothermal process. The obtained Bi2WO6:Eu(III) nanoparticles were characterized by XRD, SEM, luminescence spectrophotometer and DRS. The XRD and TEM results indicate that the Eu(III) doping concentration has no influence on the phase and morphology. However, the Eu(III) doping can tune the luminescence and enhance the photocatalytic activity of Bi2WO6. With the increases of Eu(3+) doping concentrations, the emission intensity of WO6(6-) group decreases nut the photocatalytic activity increases. The tunable luminescence of Bi2WO6:Eu(III) nanoparticles results from the energy transfer from WO6(6-) group to Eu(III) ion. The enhanced performance can be ascribed to efficient separation of electron and hole pairs after doping Eu(III) into the Bi2WO6 lattice.

  2. Influence of gold nanoparticle size on the orientation and activity of adsorbed proteins

    NASA Astrophysics Data System (ADS)

    Kaur, Kanwarjeet; Forrest, James

    2010-03-01

    We used UV-visible extinction spectroscopy to study the orientation and activity of rabbit immunoglobulin G and Protein A from Staphylococcus aureus adsorbed onto gold nanoparticles of various sizes (10-60nm). There is a shift in the localised surface plasmon resonance peak due to the interaction of proteins with the nanoparticles. The proteins adopt different orientations on smaller spheres as compared to larger spheres. IgG adopts end-on orientation on bigger spheres with the Fc domain directed towards the spheres. It displays no activity towards Protein A. This study shows that the curvature of nanoparticles strongly influences the orientation of adsorbed proteins. This could be useful in the designing of colloidal drug carriers.

  3. Tunable luminescence and enhanced photocatalytic activity for Eu(III) doped Bi2WO6 nanoparticles

    NASA Astrophysics Data System (ADS)

    Gu, Haidong; Yu, Lei; Wang, Juan; Ni, Min; Liu, Tingting; Chen, Feng

    2017-04-01

    A series of Eu(III) doped Bi2WO6 nanoparticles were synthesized by a hydrothermal process. The obtained Bi2WO6:Eu(III) nanoparticles were characterized by XRD, SEM, luminescence spectrophotometer and DRS. The XRD and TEM results indicate that the Eu(III) doping concentration has no influence on the phase and morphology. However, the Eu(III) doping can tune the luminescence and enhance the photocatalytic activity of Bi2WO6. With the increases of Eu3 + doping concentrations, the emission intensity of WO66 - group decreases nut the photocatalytic activity increases. The tunable luminescence of Bi2WO6:Eu(III) nanoparticles results from the energy transfer from WO66 - group to Eu(III) ion. The enhanced performance can be ascribed to efficient separation of electron and hole pairs after doping Eu(III) into the Bi2WO6 lattice.

  4. Synthesis of polyethylenimine (PEI) functionalized silver nanoparticles by a hydrothermal method and their antibacterial activity study.

    PubMed

    Liu, Zhiguo; Wang, Yuanlin; Zu, Yuangang; Fu, Yujie; Li, Na; Guo, Na; Liu, Ruisi; Zhang, Yiming

    2014-09-01

    In this study, we report a facile, one-step hydrothermal method to synthesize PEI-functionalized Ag nanoparticles in which no extra reducing agent is needed and PEI serves as a reducing agent and a stabilizing agent. The obtained Ag colloids have been characterized by TEM, UV absorption spectra and laser particle size analyzer. We found that the size of Ag nanoparticles can be tuned through the alteration of the temperature and growth mode. Under an acidic condition, PEI-functionalized Ag nanoparticles are positively charged. More importantly, the Ag colloids exhibited stronger antibacterial activity in the bactericidal test. Its bactericidal efficiency exceeds the commonly used antibacterial agents such as Erythromycin, chloramphenicol and penicillin as well as AgNO3 solution. These results prove that our synthesis method is very efficient to produce a stable PEI-functionalized Ag colloid with excellent antibacterial activity.

  5. Extracellular synthesis of silver nanoparticles by novel Pseudomonas veronii AS41G inhabiting Annona squamosa L. and their bactericidal activity

    NASA Astrophysics Data System (ADS)

    Baker, Syed; Mohan Kumar, K.; Santosh, P.; Rakshith, D.; Satish, S.

    2015-02-01

    In present investigation extracellular synthesis of silver nanoparticles were synthesized using cell free supernatant of Pseudomonas veronii AS41G isolated from Annona squamosa L. The bacterium significantly reduced silver nitrate to generate silver nanoparticles which was characterized with hyphenated techniques. Synthesis of silver nanoparticles preliminary confirmed by UV-Visible spectrophotometry with the intense peak at 410 nm, Further FTIR analysis revealed the possible role of biomolecules in the supernatant responsible for mediating the nanoparticles formation. The XRD spectra exhibited the characteristic Bragg peaks of 1 0 0, 1 1 1, 2 0 0, and 2 2 0 facets of the face centred cubic symmetry of nanoparticles suggesting that these nanoparticles were crystalline in nature. TEM microgram showed polydispersity of nanoparticles with size ranging from 5 to 50 nm. Synthesized silver nanoparticles showed antibacterial activity against human and environmental pathogens including MRSA. The study enlightens the role of biosynthesized silver nanoparticles as an emerging alternative for drug resistant microorganisms. The obtained results are promising enough to pave the environmentally benign nanoparticle synthesis processes without use of any toxic chemicals and also envision the emerging role of endophytes towards synthesis of nanoparticles. With scanty reports available on P.veronii species, a new role has been reported in this study which will be very valuable for future researchers working on it.

  6. Biogenic synthesis of silver nanoparticles using guava ( Psidium guajava) leaf extract and its antibacterial activity against Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Bose, Debadin; Chatterjee, Someswar

    2016-08-01

    Among the various inorganic nanoparticles, silver nanoparticles have received substantial attention in the field of antimicrobial research. For safe and biocompatible use of silver nanoparticles in antimicrobial research, the different biogenic routes are developed to synthesize silver nanoparticles that do not use toxic chemicals. Among those, to synthesize silver nanoparticles, the use of plant part extract becomes an emerging field because plant part acts as reducing as well as capping agent. For large-scale production of antibacterial silver nanoparticles using plant part, the synthesis route should be very simple, rapid, cost-effective and environment friendly based on easy availability and non-toxic nature of plant, stability and antibacterial potential of biosynthesized nanoparticles. In the present study, we report a very simple, rapid, cost-effective and environment friendly route for green synthesis of silver nanoparticles using guava ( Psidium guajava) leaf extract as reducing as well as capping agent. This plant has been opted for the present study for its known medicinal properties, and it is easily available in all seasons and everywhere. The biosynthesized silver nanoparticles are characterized by UV-Vis and TEM analysis. The average particle size is 40 nm in the range of 10-90 nm. The antibacterial activity of these nanoparticles against Pseudomonas aeruginosa MTCC 741 has been measured by disc diffusion method, agar cup assay and serial dilution turbidity measurement assay. The results show that green synthesized silver nanoparticles, using guava ( Psidium guajava) leaf extract, have a potential to inhibit the growth of bacteria.

  7. Photochemical conversion of solar energy.

    PubMed

    Balzani, Vincenzo; Credi, Alberto; Venturi, Margherita

    2008-01-01

    Energy is the most important issue of the 21st century. About 85% of our energy comes from fossil fuels, a finite resource unevenly distributed beneath the Earth's surface. Reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects such as pollution that threatens human health and greenhouse gases associated with global warming. Prompt global action to solve the energy crisis is therefore needed. To pursue such an action, we are urged to save energy and to use energy in more efficient ways, but we are also forced to find alternative energy sources, the most convenient of which is solar energy for several reasons. The sun continuously provides the Earth with a huge amount of energy, fairly distributed all over the world. Its enormous potential as a clean, abundant, and economical energy source, however, cannot be exploited unless it is converted into useful forms of energy. This Review starts with a brief description of the mechanism at the basis of the natural photosynthesis and, then, reports the results obtained so far in the field of photochemical conversion of solar energy. The "grand challenge" for chemists is to find a convenient means for artificial conversion of solar energy into fuels. If chemists succeed to create an artificial photosynthetic process, "... life and civilization will continue as long as the sun shines!", as the Italian scientist Giacomo Ciamician forecast almost one hundred years ago.

  8. Photochemical "triode" molecular signal transducer.

    PubMed

    Keirstead, Amy E; Bridgewater, James W; Terazono, Yuichi; Kodis, Gerdenis; Straight, Stephen; Liddell, Paul A; Moore, Ana L; Moore, Thomas A; Gust, Devens

    2010-05-12

    A molecular "hexad" in which five bis(phenylethynyl)anthracene (BPEA) fluorophores and a dithienylethene photochrome are organized by a central hexaphenylbenzene unit has been prepared. Singlet-singlet energy transfer among the BPEA units occurs on the 0.4 and 60 ps time scales, and when the dithienylethene is in the open form, the BPEA units fluoresce in the 515 nm region with a quantum yield near unity. When the dithienylethene is photoisomerized by UV light to the closed form, which absorbs in the 500-700 nm region, the closed isomer strongly quenches all of the excited singlet states of BPEA via energy transfer, causing the fluorescence quantum yield to drop to near zero. This photochemical behavior permits the hexad to function in a manner analogous to a triode vacuum tube or transistor. When a solution of the hexad is irradiated with steady-state light at 350 nm and with red light (>610 nm) of modulated intensity, the BPEA fluorescence excited by the 350 nm light is modulated accordingly. The fluorescence corresponds to the output of a triode tube or transistor and the modulated red light to the grid signal of the tube or gate voltage of the transistor. Frequency modulation, amplitude modulation, and phase modulation are all observed. The unusual ability to modulate intense, shorter-wavelength fluorescence with longer-wavelength light could be useful for the detection of fluorescence from probe molecules without interference from other emitters in biomolecular or nanotechnological applications.

  9. Shape-dependence of the thermal and photochemical reactions of methanol on nanocrystalline anatase TiO2

    NASA Astrophysics Data System (ADS)

    Bennett, David A.; Cargnello, Matteo; Diroll, Benjamin T.; Murray, Christopher B.; Vohs, John M.

    2016-12-01

    Structure-activity relationships and the influence of particle size and shape on the partial- and photo-oxidation of methanol on nanocrystalline anatase TiO2 were investigated using temperature-programmed desorption. The study employed two distinct nanoparticle morphologies: truncated bipyramids exposing primarily {101} facets, and flatter platelets exposing primarily {001} surfaces, whose nominal sizes ranged from 10 to 25 nm. The platelets were found to be more active for thermally-driven reactions, such as coupling of methoxide groups to produce dimethyl ether, and deoxygenation to produce methane. A dependence of the reactivity of {001} facets for the coupling of methoxide groups to produce dimethyl ether on facet size was also observed. In contrast to the thermally-driven reactions, the bipyramidal nanoparticles were observed to be more active for a range of photochemical reactions, including oxidation and coupling to produce methyl formate, and photo-decomposition of surface methoxide species. This study also shows how well-defined nanocrystals can be used to help bridge the materials gap between studies of single crystal model catalysts and their high surface area industrial analogs.

  10. The photochemical smog pollution in Beijing

    SciTech Connect

    Xiaoyan Tang

    1996-12-31

    The photochemical smog pollution in summer time has been studied in Beijing area. The systematic field measurements associated with meteorological observation was conducted in 1986, 1987 and 1993. The spatial and temporal distribution of O{sub 3} and specific formation condition of photochemical smog, including vehicle emission sources and meteorological factors etc. in summer were studied and discussed. The prediction of O{sub 3} ambient air concentration in Beijing area in 2000, 2005 and 2010 by model simulation were also discussed.

  11. Halloysite Nanotubes Supported Ag and ZnO Nanoparticles with Synergistically Enhanced Antibacterial Activity.

    PubMed

    Shu, Zhan; Zhang, Yi; Yang, Qian; Yang, Huaming

    2017-12-01

    Novel antimicrobial nanocomposite incorporating halloysite nanotubes (HNTs) and silver (Ag) into zinc oxide (ZnO) nanoparticles is prepared by integrating HNTs and decorating Ag nanoparticles. ZnO nanoparticles (ZnO NPs) and Ag nanoparticles (Ag NPs) with a size of about 100 and 8 nm, respectively, are dispersively anchored onto HNTs. The synergistic effects of ZnO NPs, Ag NPs, and HNTs led to the superior antibacterial activity of the Ag-ZnO/HNTs antibacterial nanocomposites. HNTs facilitated the dispersion and stability of ZnO NPs and brought them in close contact with bacteria, while Ag NPs could promote the separation of photogenerated electron-hole pairs and enhanced the antibacterial activity of ZnO NPs. The close contact with cell membrane enabled the nanoparticles to produce the increased concentration of reactive oxygen species and the metal ions to permeate into the cytoplasm, thus induced quick death of bacteria, indicating that Ag-ZnO/HNTs antibacterial nanocomposite is a promising candidate in the antibacterial fields.

  12. Halloysite Nanotubes Supported Ag and ZnO Nanoparticles with Synergistically Enhanced Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Shu, Zhan; Zhang, Yi; Yang, Qian; Yang, Huaming

    2017-02-01

    Novel antimicrobial nanocomposite incorporating halloysite nanotubes (HNTs) and silver (Ag) into zinc oxide (ZnO) nanoparticles is prepared by integrating HNTs and decorating Ag nanoparticles. ZnO nanoparticles (ZnO NPs) and Ag nanoparticles (Ag NPs) with a size of about 100 and 8 nm, respectively, are dispersively anchored onto HNTs. The synergistic effects of ZnO NPs, Ag NPs, and HNTs led to the superior antibacterial activity of the Ag-ZnO/HNTs antibacterial nanocomposites. HNTs facilitated the dispersion and stability of ZnO NPs and brought them in close contact with bacteria, while Ag NPs could promote the separation of photogenerated electron-hole pairs and enhanced the antibacterial activity of ZnO NPs. The close contact with cell membrane enabled the nanoparticles to produce the increased concentration of reactive oxygen species and the metal ions to permeate into the cytoplasm, thus induced quick death of bacteria, indicating that Ag-ZnO/HNTs antibacterial nanocomposite is a promising candidate in the antibacterial fields.

  13. Aluminum hydroxide nanoparticles show a stronger vaccine adjuvant activity than traditional aluminum hydroxide microparticles.

    PubMed

    Li, Xinran; Aldayel, Abdulaziz M; Cui, Zhengrong

    2014-01-10

    Aluminum hydroxide is used as a vaccine adjuvant in various human vaccines. Unfortunately, despite its favorable safety profile, aluminum hydroxide can only weakly or moderately potentiate antigen-specific antibody responses. When dispersed in an aqueous solution, aluminum hydroxide forms particulates of 1-20μm. There is increasing evidence that nanoparticles around or less than 200nm as vaccine or antigen carriers have a more potent adjuvant activity than large microparticles. In the present study, we synthesized aluminum hydroxide nanoparticles of 112nm. Using ovalbumin and Bacillus anthracis protective antigen protein as model antigens, we showed that protein antigens adsorbed on the aluminum hydroxide nanoparticles induced a stronger antigen-specific antibody response than the same protein antigens adsorbed on the traditional aluminum hydroxide microparticles of around 9.3μm. The potent adjuvant activity of the aluminum hydroxide nanoparticles was likely related to their ability to more effectively facilitate the uptake of the antigens adsorbed on them by antigen-presenting cells. Finally, the local inflammation induced by aluminum hydroxide nanoparticles in the injection sites was milder than that induced by microparticles. Simply reducing the particle size of the traditional aluminum hydroxide adjuvant into nanometers represents a novel and effective approach to improve its adjuvanticity.

  14. Biosynthesis of copper nanoparticles and its effect on actively dividing cells of mitosis in Allium cepa.

    PubMed

    Nagaonkar, Dipali; Shende, Sudhir; Rai, Mahendra

    2015-01-01

    Nanobiotechnological application of copper nanoparticles has paved the way for advancement in agriculture owing to its bactericidal and fungicidal activities. Recently, researchers have focussed on bioinspired synthesis of copper nanoparticles as a viable alternative to existing physicochemical techniques. For the commercialization of nanocopper, the toxicity evaluation is a major issue. In this context, Citrus medica (L.) fruit extract-mediated copper nanoparticles were synthesized and its different concentrations (10, 20, 40, 60, 80, and 100 µg mL(-1) ) were evaluated for its effect on actively dividing cells of Allium cepa. The study clearly revealed that copper nanoparticles increased mitotic index up to the concentration of 20 µg mL(-1) . In addition, a gradual decline in mitotic index and increase in abnormality index was observed as the concentration of copper nanoparticles and treatment duration were increased. Aberrations in chromosomal behavior such as sticky and disturbed chromosomes in metaphase and anaphase, c-metaphase, bridges, laggard, disturbed telophase, and vacuolated nucleus were also observed.

  15. Biogenic synthesis of zinc oxide nanoparticles using Ruta graveolens (L.) and their antibacterial and antioxidant activities

    NASA Astrophysics Data System (ADS)

    Lingaraju, K.; Raja Naika, H.; Manjunath, K.; Basavaraj, R. B.; Nagabhushana, H.; Nagaraju, G.; Suresh, D.

    2016-06-01

    In the present investigation, green synthesis of zinc oxide nanoparticles were successfully synthesized by biological method using aqueous stem extract of Ruta graveolens act as reducing agent. Formation of ZnO nanoparticles were characterized by powder X-ray diffraction (PXRD), UV-visible spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Zinc oxide nanoparticles were subjected to biological properties such as antibacterial and antioxidant studies. The PXRD pattern reveals that ZnO sample belongs to hexagonal phase with Wurtzite structure. The UV-vis absorption spectrum shows an absorption band at 355 nm due to ZnO nanoparticles. SEM images show that the particles have spherical like structure with large surface area and the average crystallite sizes were found to be in the range ~28 nm. These observations were confirmed by TEM analysis. The ZnO nanoparticles are found to inhibit the antioxidant activity of 1,1-diphenyl-2-picrylhydrazyl free radicals effectively. ZnO Nps exhibit significant bactericidal activity against Gram -ve bacterial strains such as Klebsiella aerogenes, Pseudomonas aeruginosa, Escherichia coli and Gram +ve Staphylococcus aureus by agar well diffusion method.

  16. Metal nanoparticle/ionic liquid/cellulose: new catalytically active membrane materials for hydrogenation reactions.

    PubMed

    Gelesky, Marcos A; Scheeren, Carla W; Foppa, Lucas; Pavan, Flavio A; Dias, Silvio L P; Dupont, Jairton

    2009-07-13

    Transition metal-containing membrane films of 10, 20, and 40 μm thickness were obtained by the combination of irregularly shaped nanoparticles with monomodal size distributions of 4.8 ± 1.1 nm (Rh(0)) and 3.0 ± 0.4 nm (Pt(0)) dispersed in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide (BMI·(NTf)(2)) with a syrup of cellulose acetate (CA) in acetone. The Rh(0) and Pt(0) metal concentration increased proportionally with increases in film thickness up to 20 μm, and then the material became metal saturated. The presence of small and stable Rh(0) or Pt(0) nanoparticles induced an augmentation in the CA/IL film surface areas. The augmentation of the IL content resulted in an increase of elasticity and decrease in tenacity and toughness, whereas the stress at break was not influenced. The introduction of IL probably causes an increase in the separation between the cellulose macromolecules that results in a higher flexibility, lower viscosity, and better formability of the cellulose material. The nanoparticle/IL/CA combinations exhibit an excellent synergistic effect that enhances the activity and durability of the catalyst for the hydrogenation of cyclohexene. The nanoparticle/IL/cellulose acetate film membranes display higher catalytic activity (up to 7353 h(-1) for the 20 μm film of CA/IL/Pt(0)) and stability than the nanoparticles dispersed only in the IL.

  17. Antimicrobial, Antioxidant and Cytotoxic Activity of Silver Nanoparticles Synthesized by Leaf Extract of Erythrina suberosa (Roxb.)

    PubMed Central

    Mohanta, Yugal K.; Panda, Sujogya K.; Jayabalan, Rasu; Sharma, Nanaocha; Bastia, Akshaya K.; Mohanta, Tapan K.

    2017-01-01

    In this experiment, biosynthesized silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of Erythrina suberosa (Roxb.). The biosynthesis of silver nanoparticle was continuously followed by UV-vis spectrophotometric analysis. The response of the phytoconstituents resides in E. suberusa during synthesis of stable AgNPs were analyzed by ATR- fourier-transform infrared spectroscopy. Further, the size, charge, and polydispersity nature of AgNPs were studied using dynamic light scattering spectroscopy. The morphology of the nanoparticles was determined by scanning electron microscopy. Current result shows core involvement of plant extracts containing glycosides, flavonoids, and phenolic compounds played a crucial role in the biosynthesis of AgNPs. The antimicrobial activities of silver nanoparticles were evaluated against different pathogenic bacterium and fungi. The antioxidant property was studied by radical scavenging (DPPH) assay and cytotoxic activity was evaluated against A-431 osteosarcoma cell line by MTT assay. The characteristics of the synthesized silver nanoparticles suggest their application as a potential antimicrobial and anticancer agent. PMID:28367437

  18. Co-Cu Nanoparticles: Synthesis by Galvanic Replacement and Phase Rearrangement during Catalytic Activation.

    PubMed

    Nafria, Raquel; Genç, Aziz; Ibáñez, Maria; Arbiol, Jordi; de la Piscina, Pilar Ramírez; Homs, Narcís; Cabot, Andreu

    2016-03-08

    The control of the phase distribution in multicomponent nanomaterials is critical to optimize their catalytic performance. In this direction, while impressive advances have been achieved in the past decade in the synthesis of multicomponent nanoparticles and nanocomposites, element rearrangement during catalyst activation has been frequently overseen. Here, we present a facile galvanic replacement-based procedure to synthesize Co@Cu nanoparticles with narrow size and composition distributions. We further characterize their phase arrangement before and after catalytic activation. When oxidized at 350 °C in air to remove organics, Co@Cu core-shell nanostructures oxidize to polycrystalline CuO-Co3O4 nanoparticles with randomly distributed CuO and Co3O4 crystallites. During a posterior reduction treatment in H2 atmosphere, Cu precipitates in a metallic core and Co migrates to the nanoparticle surface to form Cu@Co core-shell nanostructures. The catalytic behavior of such Cu@Co nanoparticles supported on mesoporous silica was further analyzed toward CO2 hydrogenation in real working conditions.

  19. Mild Photochemical Biofunctionalization of Glass Microchannels.

    PubMed

    Carvalho, Rui Rijo; Pujari, Sidharam P; Gahtory, Digvijay; Vrouwe, Elwin X; Albada, Bauke; Zuilhof, Han

    2017-01-10

    The ability to locally modify the inside of microfluidic channels with bioactive molecules is of ever-rising relevance. In this article, we show the direct photochemical coupling of a N-hydroxysuccinimide-terminated ω-alkene onto hydrogen-terminated silicon oxide, and its subsequent functionalization with a catalytically active DNAzyme. To achieve this local attachment of a DNAzyme, we prepared hydrogen-phenyl-terminated glass (H-Φ-glass) by the reaction of glass with H-SiPhCl2. The presence of a radical-stabilizing substituent on the Si atom (i.e., phenyl) enabled the covalent modification of bare glass substrates and of the inside of glass microchannels with a functional organic monolayer that allowed direct reaction with an amine-functionalized biomolecule. In this study, we directly attached an NHS-functionalized alkene to the modified glass surface using light with a wavelength of 328 nm, as evidenced by SCA, G-ATR, XPS, SEM, AFM and fluorescence microscopy. Using these NHS-based active esters on the surface, we performed a direct localized attachment of a horseradish peroxidase (HRP)-mimicking hemin/G-quadruplex (hGQ) DNAzyme complex inside a microfluidic channel. This wall-coated hGQ DNAzyme effectively catalyzed the in-flow oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) [ABTS] in the presence of hydrogen peroxide. This proof-of-concept of mild biofunctionalization will allow the facile preparation of modified microchannels for myriad biorelevant applications.

  20. Earthworm extracts utilized in the green synthesis of gold nanoparticles capable of reinforcing the anticoagulant activities of heparin

    NASA Astrophysics Data System (ADS)

    Kim, Hee Kyeong; Choi, Myung-Jin; Cha, Song-Hyun; Koo, Yean Kyoung; Jun, Sang Hui; Cho, Seonho; Park, Youmie

    2013-12-01

    Gold nanoparticles were obtained using a green synthesis approach with aqueous earthworm extracts without any additional reducing or capping agents. The gold nanoparticles were characterized using UV-visible spectrophotometry, high-resolution transmission electron microscopy, atomic force microscopy, field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and inductively coupled plasma mass spectrometry. The anticoagulant activity of the gold nanoparticles was assessed using the activated partial thromboplastin time and was mildly enhanced by combining the gold nanoparticles with heparin. In addition to the generation of spherical nanoparticles with an average diameter of 6.13 ± 2.13 nm, cubic and block-shaped nanoparticles with an average aspect ratio, defined as the length divided by width, of 1.47 were also observed.

  1. Earthworm extracts utilized in the green synthesis of gold nanoparticles capable of reinforcing the anticoagulant activities of heparin

    PubMed Central

    2013-01-01

    Gold nanoparticles were obtained using a green synthesis approach with aqueous earthworm extracts without any additional reducing or capping agents. The gold nanoparticles were characterized using UV-visible spectrophotometry, high-resolution transmission electron microscopy, atomic force microscopy, field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and inductively coupled plasma mass spectrometry. The anticoagulant activity of the gold nanoparticles was assessed using the activated partial thromboplastin time and was mildly enhanced by combining the gold nanoparticles with heparin. In addition to the generation of spherical nanoparticles with an average diameter of 6.13 ± 2.13 nm, cubic and block-shaped nanoparticles with an average aspect ratio, defined as the length divided by width, of 1.47 were also observed. PMID:24369090

  2. Solid lipid nanoparticles containing copaiba oil and allantoin: development and role of nanoencapsulation on the antifungal activity.

    PubMed

    Svetlichny, G; Külkamp-Guerreiro, I C; Cunha, S L; Silva, F E K; Bueno, K; Pohlmann, A R; Fuentefria, A M; Guterres, S S

    2015-03-01

    The aim of this work was to develop solid lipid nanoparticles (SLN) containing copaiba oil with and without allantoin (NCOA, NCO, respectively) and to evaluate their antifungal activity. Nanoparticle suspensions were prepared using a high homogenisation technique and characterised by dynamic light scattering, laser diffraction, nanoparticle tracking analysis, multiple light scattering analysis, high-pressure liquid chromatography, pH and rheology. The antifungal activities of the formulations were tested in vitro against the emergent yeasts Candida krusei and Candida parapsilosis, and the fungal pathogens of human skin Trichophyton rubrum and Microsporum canis. The dynamic light scattering analysis showed z-average diameters (intensity) between 118.63 ± 8.89 nm for the nanoparticles with both copaiba oil and allantoin and 126.06 ± 9.84nm for the nanoparticles with just copaiba oil. The D[4,3] determined by laser diffraction showed similar results of 123 ± 1.73 nm for the nanoparticles with copaiba oil and allantoin and 130 ± 3.6 nm for the nanoparticles with copaiba oil alone. Nanoparticle tracking analysis demonstrated that both suspensions had monomodal profiles and consequently, the nanoparticle populations were homogeneous. This analysis also corroborated the results of dynamic light scattering and laser diffraction, exhibiting a smaller mean diameter for the nanoparticles with copaiba oil and allantoin (143 nm) than for the nanoparticles with copaiba oil (204 nm). The physicochemical properties indicated that the dispersions were stable overtime. Rheology evidenced Newtonian behaviour for both suspensions. Antifungal susceptibility showed a MIC90 of 125 μg/mL (nanoparticles with copaiba oil) and 7.8 μg/mL (nanoparticles with copaiba oil and allantoin) against C. parapsilosis. The nanoparticles with copaiba oil and the nanoparticles with copaiba oil and allantoin presented a MIC90 of 500 μg/mL and 250 μg/mL, respectively, against C. krusei. The MIC90

  3. Intrinsic relation between catalytic activity of CO oxidation on Ru nanoparticles and Ru oxides uncovered with ambient pressure XPS.

    PubMed

    Qadir, Kamran; Joo, Sang Hoon; Mun, Bongjin S; Butcher, Derek R; Renzas, J Russell; Aksoy, Funda; Liu, Zhi; Somorjai, Gabor A; Park, Jeong Young

    2012-11-14

    Recent progress in colloidal synthesis of nanoparticles with well-controlled size, shape, and composition, together with development of in situ surface science characterization tools, such as ambient pressure X-ray photoelectron spectroscopy (APXPS), has generated new opportunities to unravel the surface structure of working catalysts. We report an APXPS study of Ru nanoparticles to investigate catalytically active species on Ru nanoparticles under oxidizing, reducing, and CO oxidation reaction conditions. The 2.8 and 6 nm Ru nanoparticle model catalysts were synthesized in the presence of poly(vinyl pyrrolidone) polymer capping agent and deposited onto a flat Si support as two-dimensional arrays using the Langmuir-Blodgett deposition technique. Mild oxidative and reductive characteristics indicate the formation of surface oxide on the Ru nanoparticles, the thickness of which is found to be dependent on nanoparticle size. The larger 6 nm Ru nanoparticles were oxidized to a smaller extent than the smaller Ru 2.8 nm nanoparticles within the temperature range of 50-200 °C under reaction conditions, which appears to be correlated with the higher catalytic activity of the bigger nanoparticles. We found that the smaller Ru nanoparticles form bulk RuO(2) on their surfaces, causing the lower catalytic activity. As the size of the nanoparticle increases, the core-shell type RuO(2) becomes stable. Such in situ observations of Ru nanoparticles are useful in identifying the active state of the catalysts during use and, hence, may allow for rational catalyst designs for practical applications.

  4. Antibacterial Activity of Polyaniline Coated Silver Nanoparticles Synthesized from Piper Betle Leaves Extract.

    PubMed

    Mamun Or Rashida, Md; Shafiul Islam, Md; Azizul Haque, Md; Arifur Rahman, Md; Tanvir Hossain, Md; Abdul Hamid, Md

    2016-01-01

    Plants or natural resources have been found to be a good alternative method for nanoparticles synthesis. In this study, polyaniline coated silver nanoparticles (AgNPs) synthesized from Piper betle leaves extract were investigated for their antibacterial activity. Silver nanoparticles were prepared from the reduction of silver nitrate and NaBH4 was used as reducing agent. Silver nanoparticles and extracts were mixed thoroughly and then coated by polyaniline. Prepared nanoparticles were characterized by Visual inspection, Ultraviolet-visible spectroscopy (UV), Fourier transform infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) techniques. Antibacterial activities of the synthesized silver nanoparticles were tested against Staphylococcus aureus ATCC 25923, Salmonella typhi ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. UV-Vis spectrum of reaction mixture showed strong absorption peak with centering at 400 nm. The FT-IR results imply that Ag-NPs were successfully synthesized and capped with bio-compounds present in P. betle. TEM image showed that Ag-NPs formed were well dispersed with a spherical structures and particle size ranging from 10 to 30 nm. The result revealed that Ag-Extract NPs showed 32.78±0.64 mm zone of inhibition against S. aureus, whereas norfloxacin (positive control) showed maximum 32.15±0.40 mm zone of inhibition for S. aureus. Again, maximum zone of inhibition 29.55±0.45 mm was found for S. typhi, 27.12±0.38 mm for E. coli and 21.95±0.45 mm for P. aeruginosa. The results obtained by this study can't be directly extrapolated to human; so further studies should be undertaken to established the strong antimicrobial activity of Ag-Extract NPs for drug development program.

  5. Antibacterial Activity of Polyaniline Coated Silver Nanoparticles Synthesized from Piper Betle Leaves Extract

    PubMed Central

    Mamun Or Rashida, Md.; Shafiul Islam, Md.; Azizul Haque, Md.; Arifur Rahman, Md.; Tanvir Hossain, Md.; Abdul Hamid, Md.

    2016-01-01

    Plants or natural resources have been found to be a good alternative method for nanoparticles synthesis. In this study, polyaniline coated silver nanoparticles (AgNPs) synthesized from Piper betle leaves extract were investigated for their antibacterial activity. Silver nanoparticles were prepared from the reduction of silver nitrate and NaBH4 was used as reducing agent. Silver nanoparticles and extracts were mixed thoroughly and then coated by polyaniline. Prepared nanoparticles were characterized by Visual inspection, Ultraviolet-visible spectroscopy (UV), Fourier transform infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) techniques. Antibacterial activities of the synthesized silver nanoparticles were tested against Staphylococcus aureus ATCC 25923, Salmonella typhi ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. UV–Vis spectrum of reaction mixture showed strong absorption peak with centering at 400 nm. The FT-IR results imply that Ag-NPs were successfully synthesized and capped with bio-compounds present in P. betle. TEM image showed that Ag-NPs formed were well dispersed with a spherical structures and particle size ranging from 10 to 30 nm. The result revealed that Ag-Extract NPs showed 32.78±0.64 mm zone of inhibition against S. aureus, whereas norfloxacin (positive control) showed maximum 32.15±0.40 mm zone of inhibition for S. aureus. Again, maximum zone of inhibition 29.55±0.45 mm was found for S. typhi, 27.12±0.38 mm for E. coli and 21.95±0.45 mm for P. aeruginosa. The results obtained by this study can’t be directly extrapolated to human; so further studies should be undertaken to established the strong antimicrobial activity of Ag-Extract NPs for drug development program. PMID:27642330

  6. Deposition of silver nanoparticles on dendrimer functionalized multiwalled carbon nanotubes: synthesis, characterization and antimicrobial activity.

    PubMed

    Neelgund, Gururaj M; Oki, Aderemi

    2011-04-01

    The nanohybrids composed of silver nanoparticles and aromatic polyamide functionalized multiwalled carbon nanotubes (MWCNTs) is successfully synthesized and tested for their antibacterial activity against different pathogens. Prior to deposition of silver nanoparticles, acid treated MWCNTs (MWCNTs-COOH) were successively reacted with p-phenylenediamine and methylmethacrylate to form series of NH2-terminated aromatic polyamide dendrimers on the surface of MWCNTs through Michael addition and amidation. Existence of high abundance of amine groups on the surface of functionalized MWCNTs (f-MWCNTs) provided sites for formation of silver nanoparticles by the reduction of aqueous solution of AgNO3. The silver nanoparticles formed in the resulted f-MWCNTs-Ag nanohybrids were determined to be face centered cubic (fcc) symmetry. The structure and nature of f-MWCNTs and f-MWCNTs-Ag nanohybrids were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction analysis (XRD), Raman spectroscopy and thermogravimetric analysis (TGA). The dispersion state of f-MWCNTs and immobilization of silver nanoparticles on the surface of f-MWCNTs were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Elemental composition of f-MWCNTs-Ag nanohybrids was determined by energy dispersive X-ray spectroscopy (EDS). The antimicrobial activity of f-MWCNTs-Ag nanohybrids were estimated against E. coli, P. aeruginosa and S. aureu and compared with MWCNTs-COOH and f-MWCNTs. The results indicate that functionalization of MWCNTs with aromatic polyamide dendrimers and successive deposition of Ag nanoparticles could play an important role in the enhancement of antimicrobial activity.

  7. Facile, one-pot synthesis, and antibacterial activity of mesoporous silica nanoparticles decorated with well-dispersed silver nanoparticles.

    PubMed

    Tian, Yue; Qi, Juanjuan; Zhang, Wei; Cai, Qiang; Jiang, Xingyu

    2014-08-13

    In this study, we exploit a facile, one-pot method to prepare MCM-41 type mesoporous silica nanoparticles decorated with silver nanoparticles (Ag-MSNs). Silver nanoparticles with diameter of 2-10 nm are highly dispersed in the framework of mesoporous silica nanoparticles. These Ag-MSNs possess an enhanced antibacterial effect against both Gram-positive and Gram-negative bacteria by preventing the aggregation of silver nanoparticles and continuously releasing silver ions for one month. The cytotoxicity assay indicates that the effective antibacterial concentration of Ag-MSNs shows little effect on human cells. This report describes an efficient and economical route to synthesize mesoporous silica nanoparticles with uniform silver nanoparticles, and these nanoparticles show promising applications as antibiotics.

  8. Proximity-activated nanoparticles: in vitro performance of specific structural modification by enzymatic cleavage

    PubMed Central

    Adam Smith, R; Sewell, Sarah L; Giorgio, Todd D

    2008-01-01

    The development and in vitro performance of a modular nanoscale system capable of specific structural modification by enzymatic activity is described in this work. Due to its small physical size and adaptable characteristics, this system has the potential for utilization in targeted delivery systems and biosensing. Nanoparticle probes were synthesized containing two distinct fluorescent species including a quantum dot base particle and fluorescently labeled cleavable peptide substrate. Activity of these probes was monitored by gel electrophoresis with quantitative cleavage measurements made by fluorometric analysis. The model proximity-activated nanoparticles studied here exhibit significant susceptibility to cleavage by matrix metalloprotease-7 (MMP-7) at physiologically relevant concentrations, with nearly complete cleavage of available substrate molecules after 24 hours. This response is specific to MMP-7 enzyme activity, as cleavage is completely inhibited with the addition of EDTA. Utilization of enzyme-specific modification is a sensitive approach with broad applications for targeted therapeutics and biosensing. The versatility of this nanoparticle system is highlighted in its modular design, as it has the capability to integrate characteristics for detection, biosensing, targeting, and payload delivery into a single, multifunctional nanoparticle structure. PMID:18488420

  9. Aptamer-mediated 'turn-off/turn-on' nanozyme activity of gold nanoparticles for kanamycin detection.

    PubMed

    Sharma, Tarun Kumar; Ramanathan, Rajesh; Weerathunge, Pabudi; Mohammadtaheri, Mahsa; Daima, Hemant Kumar; Shukla, Ravi; Bansal, Vipul

    2014-12-28

    A new ultrafast and highly sensitive 'turn-off/turn-on' biosensing approach that combines the intrinsic peroxidase-like activity of gold nanoparticles (GNPs) with the high affinity and specificity of a ssDNA aptamer is presented for the efficient detection of a model small molecule kanamycin.

  10. Delivery of a Protease-Activated Cytolytic Peptide Prodrug by Perfluorocarbon Nanoparticles.

    PubMed

    Jallouk, Andrew P; Palekar, Rohun U; Marsh, Jon N; Pan, Hua; Pham, Christine T N; Schlesinger, Paul H; Wickline, Samuel A

    2015-08-19

    Melittin is a cytolytic peptide derived from bee venom that inserts into lipid membranes and oligomerizes to form membrane pores. Although this peptide is an attractive candidate for treatment of cancers and infectious processes, its nonspecific cytotoxicity and hemolytic activity have limited its therapeutic applications. Several groups have reported the development of cytolytic peptide prodrugs that only exhibit cytotoxicity following activation by site-specific proteases. However, systemic administration of these constructs has proven difficult because of their poor pharmacokinetic properties. Here, we present a platform for the design of protease-activated melittin derivatives that may be used in conjunction with a perfluorocarbon nanoparticle delivery system. Although native melittin was substantially hemolytic (HD50: 1.9 μM) and cytotoxic (IC50: 2.4 μM), the prodrug exhibited 2 orders of magnitude less hemolytic activity (HD50: > 100 μM) and cytotoxicity (IC50: > 100 μM). Incubation with matrix metalloproteinase-9 (MMP-9) led to cleavage of the prodrug at the expected site and restoration of hemolytic activity (HD50: 3.4 μM) and cytotoxicity (IC50: 8.1 μM). Incubation of the prodrug with perfluorocarbon nanoparticles led to stable loading of 10,250 peptides per nanoparticle. Nanoparticle-bound prodrug was also cleaved and activated by MMP-9, albeit at a fourfold slower rate. Intravenous administration of prodrug-loaded nanoparticles in a mouse model of melanoma significantly decreased tumor growth rate (p = 0.01). Because MMPs and other proteases play a key role in cancer invasion and metastasis, this platform holds promise for the development of personalized cancer therapies directed toward a patient's individual protease expression profile.

  11. Enhancing the Anti-Enterococci Activity of Different Antibiotics by Combining With Metal Oxide Nanoparticles

    PubMed Central

    Iram, Saira; Akbar Khan, Jawad; Aman, Nargis; Nadhman, Akhtar; Zulfiqar, Zikra; Arfat Yameen, Muhammad

    2016-01-01

    Background Enterococci have emerged as more virulent and multidrug-resistant in community and hospital settings. The emergence of vancomycin resistant enterococci (VRE) in hospitals has posed a serious threat to public health. The widespread use of antibiotics to treat VRE infections has resulted in the development of resistant forms of these organisms. Objectives Present study deals with the efficacy of antibiotic-nanoparticle combination against clinical isolates of VRE. This study has effectively evaluated the anti-enterococcal activity of metallic nanoparticles and their combination with antibiotics with the aim to search for new biocidal combinations. Materials and Methods Initially, the isolates were identified by various biochemical tests and also by PCR, targeting ddl, vanA and vanB genes. Antibiotic susceptibility testing was carried out by disc diffusion method. Minimum inhibitory concentration (MIC) of both antibiotics and metal nanoparticles against VRE was done using broth dilution method. On the basis of MICs, a combination of both antibiotics and nanoparticles was used by physical mixing of antibiotics and different concentrations of nanoparticles. Results The MIC of metal nanoparticles were found in the range of 0.31 - 30 mM. The combination of both antibiotics and nanoparticles has effectively reduced the MICs of ciprofloxacin from 16 - 256 μg/mL to 2 - 16 μg/mL, erythromycin 1024 - 2048 μg/mL to 128 - 512 μg/mL, methicillin 32 - 256 μg/mL to 8 - 64 μg/mL and vancomycin 2 - 512 μg/mL to 0.5 - 64 μg/mL. Conclusions Among the nanoparticles, ZnO was found as a potent metallic nanoparticle which effectively reduced the MIC upon combination with the antibiotics. The combination exhibited enhanced bactericidal activity against multidrug resistant clinical strains of VRE with dose dependency. Further extensive study on this aspect can prove their beneficial clinical use against resistant pathogens to combat increasing resistance to antibiotics

  12. Polymeric Nanoparticles of Brazilian Red Propolis Extract: Preparation, Characterization, Antioxidant and Leishmanicidal Activity

    NASA Astrophysics Data System (ADS)

    do Nascimento, Ticiano Gomes; da Silva, Priscilla Fonseca; Azevedo, Lais Farias; da Rocha, Louisianny Guerra; de Moraes Porto, Isabel Cristina Celerino; Lima e Moura, Túlio Flávio Accioly; Basílio-Júnior, Irinaldo Diniz; Grillo, Luciano Aparecido Meireles; Dornelas, Camila Braga; Fonseca, Eduardo Jorge da Silva; de Jesus Oliveira, Eduardo; Zhang, Alex Tong; Watson, David G.

    2016-06-01

    The ever-increasing demand for natural products and biotechnology derived from bees and ultra-modernization of various analytical devices has facilitated the rational and planned development of biotechnology products with a focus on human health to treat chronic and neglected diseases. The aim of the present study was to prepare and characterize polymeric nanoparticles loaded with Brazilian red propolis extract and evaluate the cytotoxic activity of "multiple-constituent extract in co-delivery system" for antileishmanial therapies. The polymeric nanoparticles loaded with red propolis extract were prepared with a combination of poly-ɛ-caprolactone and pluronic using nanoprecipitation method and characterized by different analytical techniques, antioxidant and leishmanicidal assay. The red propolis nanoparticles in aqueous medium presented particle size (200-280 nm) in nanometric scale and zeta analysis (-20 to -26 mV) revealed stability of the nanoparticles without aggregation phenomenon during 1 month. After freeze-drying method using cryoprotectant (sodium starch glycolate), it was possible to observe particles with smooth and spherical shape and apparent size of 200 to 400 nm. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and thermal analysis revealed the encapsulation of the flavonoids from the red propolis extract into the polymeric matrix. Ultra performance liquid chromatography coupled with diode array detector (UPLC-DAD) identified the flavonoids liquiritigenin, pinobanksin, isoliquiritigenin, formononetin and biochanin A in ethanolic extract of propolis (EEP) and nanoparticles of red propolis extract (NRPE). The efficiency of encapsulation was determinate, and median values (75.0 %) were calculated using UPLC-DAD. 2,2-Diphenyl-1-picryhydrazyl method showed antioxidant activity to EEP and red propolis nanoparticles. Compared to negative control, EEP and NRPE exhibited leishmanicidal activity with an IC50 value of ≅38.0

  13. Interactions of PLGA nanoparticles with blood components: protein adsorption, coagulation, activation of the complement system and hemolysis studies

    NASA Astrophysics Data System (ADS)

    Fornaguera, Cristina; Calderó, Gabriela; Mitjans, Montserrat; Vinardell, Maria Pilar; Solans, Conxita; Vauthier, Christine

    2015-03-01

    The intravenous administration of poly(lactic-co-glycolic) acid (PLGA) nanoparticles has been widely reported as a promising alternative for delivery of drugs to specific cells. However, studies on their interaction with diverse blood components using different techniques are still lacking. Therefore, in the present work, the interaction of PLGA nanoparticles with blood components was described using different complementary techniques. The influence of different encapsulated compounds/functionalizing agents on these interactions was also reported. It is worth noting that all these techniques can be simply performed, without the need for highly sophisticated apparatus or skills. Moreover, their transference to industries and application of quality control could be easily performed. Serum albumin was adsorbed onto all types of tested nanoparticles. The saturation concentration was dependent on the nanoparticle size. In contrast, fibrinogen aggregation was dependent on nanoparticle surface charge. The complement activation was also influenced by the nanoparticle functionalization; the presence of a functionalizing agent increased complement activation, while the addition of an encapsulated compound only caused a slight increase. None of the nanoparticles influenced the coagulation cascade at low concentrations. However, at high concentrations, cationized nanoparticles did activate the coagulation cascade. Interactions of nanoparticles with erythrocytes did not reveal any hemolysis. Interactions of PLGA nanoparticles with blood proteins depended both on the nanoparticle properties and the protein studied. Independent of their loading/surface functionalization, PLGA nanoparticles did not influence the coagulation cascade and did not induce hemolysis of erythrocytes; they could be defined as safe concerning induction of embolization and cell lysis.The intravenous administration of poly(lactic-co-glycolic) acid (PLGA) nanoparticles has been widely reported as a promising

  14. Exploitation of endophytic fungus, Guignardia mangiferae for extracellular synthesis of silver nanoparticles and their in vitro biological activities.

    PubMed

    Balakumaran, M D; Ramachandran, R; Kalaichelvan, P T

    2015-09-01

    The aim of this study was to synthesize highly biocompatible and functionalized silver nanoparticles using endophytic fungi isolated from the leaves of medicinal plants. Among 13 fungi tested, the isolate, Guignardia mangiferae (Bios PTK 4) extracellularly synthesized well-dispersed and extremely stable silver nanoparticles under optimized reaction conditions within 12 h. These nanoparticles were characterized by HR-TEM, SAED, XRD and EDX analyses. G. mangiferae synthesized 5-30 nm sized, spherical shaped silver nanoparticles. Effect of pH on the antibacterial activity of silver nanoparticles was studied using well diffusion assay; on the basis of particle stability and antibacterial activity, pH 7 was found to be optimum. The leakage of intracellular components has clearly demonstrated that silver nanoparticles damage the bacterial cells by formation of pores, which affect the membrane permeability and finally leads to cell death. In addition, silver nanoparticles exhibited excellent antifungal activity against plant pathogenic fungi. Cytotoxic effects of silver nanoparticles showed IC50 values of 63.37, 27.54 and 23.84 μg/mL against normal African monkey kidney (Vero), HeLa (cervical) and MCF-7 (breast) cells, respectively, at 24 h incubation period. Thus, the obtained results convincingly suggest that silver nanoparticles synthesized from G. mangiferae are highly biocompatible and have wider applicability and they could be explored as promising candidates for a variety of biomedical/pharmaceutical and agricultural applications.

  15. Delivery of molecules into cells using carbon nanoparticles activated by femtosecond laser pulses.

    PubMed

    Chakravarty, Prerona; Qian, Wei; El-Sayed, Mostafa A; Prausnitz, Mark R

    2010-08-01

    A major barrier to drug and gene delivery is crossing the cell's plasma membrane. Physical forces applied to cells via electroporation, ultrasound and laser irradiation generate nanoscale holes in the plasma membrane for direct delivery of drugs into the cytoplasm. Inspired by previous work showing that laser excitation of carbon nanoparticles can drive the carbon-steam reaction to generate highly controlled shock waves, we show that carbon black nanoparticles activated by femtosecond laser pulses can facilitate the delivery of small molecules, proteins and DNA into two types of cells. Our initial results suggest that interaction between the laser energy and carbon black nanoparticles may generate photoacoustic forces by chemical reaction to create transient holes in the membrane for intracellular delivery.

  16. Recent Developments in Active Tumor Targeted Multifunctional Nanoparticles for Combination Chemotherapy in Cancer Treatment and Imaging

    PubMed Central

    Glasgow, Micah D. K.; Chougule, Mahavir B.

    2016-01-01

    Nanotechnology and combination therapy are two major fields that show great promise in the treatment of cancer. The delivery of drugs via nanoparticles helps to improve drug’s therapeutic effectiveness while reducing adverse side effects associated with high dosage by improving their pharmacokinetics. Taking advantage of molecular markers over-expressing on tumor tissues compared to normal cells, an “active” molecular marker targeted approach would be beneficial for cancer therapy. These actively targeted nanoparticles would increase drug concentration at the tumor site, improving efficacy while further reducing chemo-resistance. The multidisciplinary approach may help to improve the overall efficacy in cancer therapy. This review article summarizes recent developments of targeted multifunctional nanoparticles in the delivery of various drugs for a combinational chemotherapy approach to cancer treatment and imaging. PMID:26554150

  17. Probing the Raman-active acoustic vibrations of nanoparticles with extraordinary spectral resolution

    NASA Astrophysics Data System (ADS)

    Wheaton, Skyler; Gelfand, Ryan M.; Gordon, Reuven

    2015-01-01

    Colloidal quantum dots, viruses, DNA and all other nanoparticles have acoustic vibrations that can act as ‘fingerprints’ to identify their shape, size and mechanical properties, yet high-resolution Raman spectroscopy in this low-energy range has been lacking. Here, we demonstrate extraordinary acoustic Raman (EAR) spectroscopy to measure the Raman-active vibrations of single isolated nanoparticles in the 0.1-10 cm-1 range with ˜0.05 cm-1 resolution, to resolve peak splitting from material anisotropy and to probe the low-frequency modes of biomolecules. EAR employs a nanoaperture laser tweezer that can select particles of interest and manipulate them once identified. We therefore believe that this nanotechnology will enable expanded capabilities for the study of nanoparticles in the materials and life sciences.

  18. Evaluation of larvicidal activity of biogenic nanoparticles against filariasis causing Culex mosquito vector

    PubMed Central

    Dhanasekaran, Dharumadurai; Thangaraj, Ramasamy

    2013-01-01

    Objective To evaluate the larvicidal activity of biogenic nanoparticles against filariasis causing Culex mosquito vector. Methods The synthesized AgNPs were characterized by UV-vis. spectrum, Fourier transform infrared and X-ray diffraction. Larvae were exposed to varying concentrations of aqueous extract of synthesized AgNPs for 10 min. The different concentrations of 5, 2.5, 1.25, 0.625 and 0.312 mg/L silver nanoparticles were tested against the Culex larvae. Results The mortality rate of Agaricus bisporus biogenic nanoparticles against Culex larvae are 5 mg/L (100%), 2.5 mg/L (81%), 1.25 mg/L (62%), 0.625 mg/L (28%) and 0.312 mg/L (11%). Conclusions These results suggest that the synthesized biogenic AgNPs have the potential to be used as an ideal eco-friendly approach for controlling Culex larvae.

  19. Biocompatible and biodegradable nanoparticles for enhancement of anti-cancer activities of phytochemicals.

    PubMed

    Li, Chuan; Zhang, Jia; Zu, Yu-Jiao; Nie, Shu-Fang; Cao, Jun; Wang, Qian; Nie, Shao-Ping; Deng, Ze-Yuan; Xie, Ming-Yong; Wang, Shu

    2015-09-01

    Many phytochemicals show promise in cancer prevention and treatment, but their low aqueous solubility, poor stability, unfavorable bioavailability, and low target specificity make administering them at therapeutic doses unrealistic. This is particularly true for (-)-epigallocatechin gallate, curcumin, quercetin, resveratrol, and genistein. There is an increasing interest in developing novel delivery strategies for these natural products. Liposomes, micelles, nanoemulsions, solid lipid nanoparticles, nanostructured lipid carriers and poly (lactide-co-glycolide) nanoparticles are biocompatible and biodegradable nanoparticles. Those nanoparticles can increase the stability and solubility of phytochemicals, exhibit a sustained release property, enhance their absorption and bioavailability, protect them from premature enzymatic degradation or metabolism, prolong their circulation time, improve their target specificity to cancer cells or tumors via passive or targeted delivery, lower toxicity or side-effects to normal cells or tissues through preventing them from prematurely interacting with the biological environment, and enhance anti-cancer activities. Nanotechnology opens a door for developing phytochemical-loaded nanoparticles for prevention and treatment of cancer.

  20. Preparation, characterisation and antibacterial activity of a florfenicol-loaded solid lipid nanoparticle suspension.

    PubMed

    Wang, Ting; Chen, Xiaojin; Lu, Mengmeng; Li, Xihe; Zhou, WenZhong

    2015-12-01

    A florfenicol-loaded solid lipid nanoparticle (FFC-SLN) suspension was prepared by hot homogenisation and ultrasonic technique. The suspension was characterised for its release profile, stability, toxicity, and the physicochemical properties of the nanoparticles. Antibacterial activity of the suspension was evaluated in vitro and in vivo. The results showed that the mean diameter, polydispersity index and zeta potential of the nanoparticles were 253 ± 3 nm, 0.409 ± 0.022 and 47.5 ± 0.21 mV, respectively. In vitro release profile showed the FFC-SLN suspension had sustained release effect. The minimum inhibition concentration values of the FFC-SLN suspension were 6 and 3 µg/mL against Staphylococcus aureus and Escherichia coli respectively, compared with 3.5 and 2 µg/mL of native florfenicol. The suspension was relatively stable at 4°C and less stable at room temperature during 9 months storage. Although the nanoparticle carriers exhibited cytotoxicity in cell cultures, the LD50 of the lyophilised dry power of the suspension was higher than 5 g/kg body weight. Mortality protection against E. coli lethal infection in mice showed that the nanoparticle suspension had much better efficacy (6/10) than native drug (1/10). These results indicate that FFC-SLN suspension could be a promising formulation in veterinary medicine.

  1. In Vitro Antibacterial Activity and Mechanism of Silver Nanoparticles against Foodborne Pathogens.

    PubMed

    Rajeshkumar, S; Malarkodi, C

    2014-01-01

    Biosynthesis of silver nanoparticles using Planomicrobium sp. and to explore the antibacterial activity against food borne pathogenic bacteria Bacillus subtilis, (3053) Klebsiella planticola (2727) Klebsiella pneumoniae (MAA) Serratia nematodiphila (CAA) and Escherichia coli. In the current studies, 1 mM of silver nitrate was added into 100 mL of Planomicrobium sp. culture supernatant. The bioreduction of pure AgNO3 was characterized by UV-visible spectroscopy, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy-dispersive analysis (EDS), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) analysis. The formation of silver nanoparticles was confirmed by the presence of an absorption peak at 400 nm using UV-visible spectrophotometry. The morphology and size of the silver nanoparticles was monitored by TEM and SEM. Crystal structure was obtained by carrying out X-ray diffraction studies and it showed face centered cubic (FCC) structure. The bactericidal effect of silver nanoparticles was compared based on diameter of inhibition zone in well method. Bacterial sensitivity to nanoparticles a key factor in manufacture the suitable for long life application in food packaging and food safety. Food safety is a worldwide health goal and the food borne diseases get a main disaster on health. Therefore, controlling of bacterial pathogens in food is credit of harms associated to health and safety.

  2. γ-Cyclodextrin capped silver nanoparticles for molecular recognition and enhancement of antibacterial activity of chloramphenicol.

    PubMed

    Gannimani, Ramesh; Ramesh, Muthusamy; Mtambo, Sphamandla; Pillay, Karen; Soliman, Mahmoud E; Govender, Patrick

    2016-04-01

    Computational studies were conducted to identify the favourable formation of the inclusion complex of chloramphenicol with cyclodextrins. The results of molecular docking and molecular dynamics predicted the strongest interaction of chloramphenicol with γ-cyclodextrin. Further, the inclusion complex of chloramphenicol with γ-cyclodextrin was experimentally prepared and a phenomenon of inclusion was verified by using different characterization techniques such as thermogravimetric analysis, differential scanning calorimetry, (1)H nuclear magnetic resonance (NMR) and two dimensional nuclear overhauser effect spectroscopy (NOESY) experiments. From these results it was concluded that γ-cyclodextrins could be an appropriate cyclodextrin polymer which can be used to functionalize chloramphenicol on the surface of silver nanoparticles. In addition, γ-cyclodextrin capped silver nanoparticles were synthesized and characterized using UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FTIR) and zeta potential analysis. Molecular recognition of chloramphenicol by these cyclodextrin capped silver nanoparticles was confirmed by surface enhanced raman spectroscopy (SERS) experiments. Synergistic antibacterial effect of chloramphenicol with γ-cyclodextrin capped silver nanoparticles was evaluated against Pseudomonas aeruginosa (ATCC 27853), Enterococcus faecalis (ATCC 5129), Klebsiella pneumoniae (ATCC 700603) and Staphylococcus aureus (ATCC 43300). The results from the antibacterial experiment were favourable thus allowing us to conclude that the approach of modifying organic drug molecules with cyclodextrin capped inorganic silver nanoparticles could help to enhance the antibacterial activity of them.

  3. Nitrophenol chemi-sensor and active solar photocatalyst based on spinel hetaerolite nanoparticles.

    PubMed

    Khan, Sher Bahadar; Rahman, Mohammed M; Akhtar, Kalsoom; Asiri, Abdullah M; Rub, Malik Abdul

    2014-01-01

    In this contribution, a significant catalyst based on spinel ZnMn2O4 composite nanoparticles has been developed for electro-catalysis of nitrophenol and photo-catalysis of brilliant cresyl blue. ZnMn2O4 composite (hetaerolite) nanoparticles were prepared by easy low temperature hydrothermal procedure and structurally characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and UV-visible spectroscopy which illustrate that the prepared material is optical active and composed of well crystalline body-centered tetragonal nanoparticles with average size of ∼ 38 ± 10 nm. Hetaerolite nanoparticles were applied for the advancement of a nitrophenol sensor which exhibited high sensitivity (1.500 µAcm(-2) mM(-1)), stability, repeatability and lower limit of detection (20.0 µM) in short response time (10 sec). Moreover, hetaerolite nanoparticles executed high solar photo-catalytic degradation when applied to brilliant cresyl blue under visible light.

  4. Maleimide activation of photon upconverting nanoparticles for bioconjugation

    NASA Astrophysics Data System (ADS)

    Liebherr, Raphaela B.; Soukka, Tero; Wolfbeis, Otto S.; Gorris, Hans H.

    2012-12-01

    Photon upconverting nanoparticles (UCNPs) have become an important new class of optical labels. Their unique property of emitting visible light after photo-excitation with near-infrared radiation enables biological imaging without background interference or cell damage. Biological applications require UCNPs that are dispersible in water and allow the attachment of biomolecules. Oleic acid-coated UCNPs obtained by solvothermal synthesis were functionalized with both hydrophilic PEG and thiol-reactive maleimides, either by ligand exchange or by silanization. Three different types of maleimide-functionalized UCNPs were prepared and characterized by transmission electron microscopy, dynamic light scattering and Raman spectroscopy. Ligand exchange of oleic acid by maleimide-PEG-COOH yielded UCNPs that did not aggregate, were colloidally stable and reacted readily with proteins. Such luminescent labels are required for background-free imaging and many other bioanalytical applications.

  5. Magnetic nanoparticle imaging using multiple electron paramagnetic resonance activation sequences

    SciTech Connect

    Coene, A. Dupré, L.; Crevecoeur, G.

    2015-05-07

    Magnetic nanoparticles play an important role in several biomedical applications such as hyperthermia, drug targeting, and disease detection. To realize an effective working of these applications, the spatial distribution of the particles needs to be accurately known, in a non-invasive way. Electron Paramagnetic Resonance (EPR) is a promising and sensitive measurement technique for recovering these distributions. In the conventional approach, EPR is applied with a homogeneous magnetic field. In this paper, we employ different heterogeneous magnetic fields that allow to stabilize the solution of the associated inverse problem and to obtain localized spatial information. A comparison is made between the two approaches and our novel adaptation shows an average increase in reconstruction quality by 5% and is 12 times more robust towards noise. Furthermore, our approach allows to speed up the EPR measurements while still obtaining reconstructions with an improved accuracy and noise robustness compared to homogeneous EPR.

  6. Enhanced photocatalytic activity of electrochemically synthesized aluminum oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Pathania, Deepak; Katwal, Rishu; Kaur, Harpreet

    2016-03-01

    In this study, aluminum oxide (Al2O3) nanoparticles (NPs) were synthesized via an electrochemical method. The effects of reaction parameters such as supporting electrolytes, solvent, current and electrolysis time on the shape and size of the resulting NPs were investigated. The Al2O3 NPs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, thermogravimetric analysis/differential thermal analysis, energy-dispersive X-ray analysis, and ultraviolet-visible spectroscopy. Moreover, the Al2O3 NPs were explored for photocatalytic degradation of malachite green (MG) dye under sunlight irradiation via two processes: adsorption followed by photocatalysis; coupled adsorption and photocatalysis. The coupled process exhibited a higher photodegradation efficiency (45%) compared to adsorption followed by photocatalysis (32%). The obtained kinetic data was well fitted using a pseudo-first-order model for MG degradation.

  7. Nanobody conjugated PLGA nanoparticles for active targeting of African Trypanosomiasis.

    PubMed

    Arias, José L; Unciti-Broceta, Juan D; Maceira, José; Del Castillo, Teresa; Hernández-Quero, José; Magez, Stefan; Soriano, Miguel; García-Salcedo, José A

    2015-01-10

    Targeted delivery of therapeutics is an alternative approach for the selective treatment of infectious diseases. The surface of African trypanosomes, the causative agents of African trypanosomiasis, is covered by a surface coat consisting of a single variant surface glycoprotein, termed VSG. This coat is recycled by endocytosis at a very high speed, making the trypanosome surface an excellent target for the delivery of trypanocidal drugs. Here, we report the design of a drug nanocarrier based on poly ethylen glycol (PEG) covalently attached (PEGylated) to poly(D,L-lactide-co-glycolide acid) (PLGA) to generate PEGylated PLGA nanoparticles. This nanocarrier was coupled to a single domain heavy chain antibody fragment (nanobody) that specifically recognizes the surface of the protozoan pathogen Trypanosoma brucei. Nanoparticles were loaded with pentamidine, the first-line drug for T. b. gambiense acute infection. An in vitro effectiveness assay showed a 7-fold decrease in the half-inhibitory concentration (IC50) of the formulation relative to free drug. Furthermore, in vivo therapy using a murine model of African trypanosomiasis demonstrated that the formulation cured all infected mice at a 10-fold lower dose than the minimal full curative dose of free pentamidine and 60% of mice at a 100-fold lower dose. This nanocarrier has been designed with components approved for use in humans and loaded with a drug that is currently in use to treat the disease. Moreover, this flexible nanobody-based system can be adapted to load any compound, opening a range of new potential therapies with application to other diseases.

  8. Photochemical Phenomenology Model for the New Millenium

    NASA Technical Reports Server (NTRS)

    Bishop, James; Evans, J. Scott

    2000-01-01

    This project tackles the problem of conversion of validated a priori physics-based modeling capabilities, specifically those relevant to the analysis and interpretation of planetary atmosphere observations, to application-oriented software for use in science and science-support activities. The software package under development, named the Photochemical Phenomenology Modeling Tool (PPMT), has particular focus on the atmospheric remote sensing data to be acquired by the CIRS instrument during the CASSINI Jupiter flyby and orbital tour of the Saturnian system. Overall, the project has followed the development outline given in the original proposal, and the Year 1 design and architecture goals have been met. Specific accomplishments and the difficulties encountered are summarized in this report. Most of the effort has gone into complete definition of the PPMT interfaces within the context of today's IT arena: adoption and adherence to the CORBA Component Model (CCM) has yielded a solid architecture basis, and CORBA-related issues (services, specification options, development plans, etc.) have been largely resolved. Implementation goals have been redirected somewhat so as to be more relevant to the upcoming CASSINI flyby of Jupiter, with focus now being more on data analysis and remote sensing retrieval applications.

  9. Ultra-efficient photocatalytic deprivation of methylene blue and biological activities of biogenic silver nanoparticles.

    PubMed

    Khan, Arif Ullah; Yuan, Qipeng; Wei, Yun; Khan, Zia Ul Haq; Tahir, Kamran; Khan, Shahab Ullah; Ahmad, Aftab; Khan, Shafiullah; Nazir, Sadia; Khan, Faheem Ullah

    2016-06-01

    Phytosynthesis of metal nanoparticles is considered as a safe, cost-effective, and green approach. In this study, silver nanoparticles (AgNPs) were successfully synthesized using the aqueous extract of Lychee (Litchi chinensis) fruit peel and an aqueous solution of silver nitrate (AgNO3). The synthesized nanoparticles were characterized by several analytical techniques i.e. UV-Vis Spectroscopy, XRD (X-ray diffraction spectroscopy), EDX (electron dispersive X-ray), SAED (selected area electron diffraction), HRTEM (high-resolution transmission electron microscopy), and FTIR (Fourier transform infrared spectroscopy). HRTEM and XRD results indicated that the prepared AgNPs are spherical in shape, well dispersed and face centered cubic crystalline. AgNPs showed potent antibacterial properties against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. The minimum inhibitory concentration (MIC) values were 125μg against E. coli and 62.5μg against both S. aureus and B. subtilis. AgNPs induce efficient cell constituent release from bacterial cells, which indicates the deterioration of cytoplasmic membrane. Moreover, antioxidant studies on the as-synthesized nanoparticles reveal efficient scavenging of the stable or harmful DPPH free radical. The cytotoxicity assay confirmed that biosynthesized AgNPs are nontoxic to normal healthy RBCs. AgNPs exhibited consistent release of Ag(+) determined by ICP-AES analysis. AgNPs exhibited extraordinary photocatalytic degradation (99.24%) of methylene blue. On the other hand, commercial silver nanoparticles have moderate biological activities against the tested bacterial strains and negligible photocatalytic degradation of methylene blue. The significant biological and photocatalytic activities of the biosynthesized silver nanoparticles are attributed to their small size, spherical morphology and high dispersion.

  10. Active control of the optical properties of nanoscale coatings using 'smart' nanoparticles

    NASA Astrophysics Data System (ADS)

    Cortie, Michael B.; Barnett, Michael; Ford, Michael J.

    2007-09-01

    Coatings that can self-modulate their optical properties as a function of an external stimulus are of significant technological interest. In this regard, the possibilities for thermo- or electrochromic materials such as VO II and WO 3 are already comparatively well-known. Here, however, we explore a new kind of 'smart' coating, based on the active control of a plasmon resonance in nanoparticles. One possible system is based on the modulation of the plasmon resonance of a precious metal nanorod or nanosphere by an active dielectric shell. The active dielectric undergoes an insulator-to-metal transition on increase of temperature which modulates the plasmon resonance of the underlying precious metal nanoparticle, thereby changing the wavelength at which its optical extinction is maximum. In the case of nanorods, the absorption maximum of the longitudinal plasmon is particularly sensitive to the aspect ratio of the nanoparticle and the dielectric properties of the environment, and may be readily tuned across the visible and near-infrared portions of the spectrum. In addition, nanoparticles of certain thermochromic dielectrics, such as VO II, are expected to have a plasmon resonance of their own which can be switched on or off by control of the temperature. We consider some of the possibilities, using both the discrete dipole approximation and the exact analytical solution due to Mie to calculate the optical properties.

  11. Preparation of albumin based nanoparticles for delivery of fisetin and evaluation of its cytotoxic activity.

    PubMed

    Ghosh, Pooja; Singha Roy, Atanu; Chaudhury, Susmitnarayan; Jana, Saikat Kumar; Chaudhury, Koel; Dasgupta, Swagata

    2016-05-01

    Fisetin is a well known flavonoid that shows several properties such as antioxidant, antiviral and anticancer activities. Its use in the pharmaceutical field is limited due to its poor aqueous solubility which results in poor bioavailability and poor permeability. The aim of our present study is to prepare fisetin loaded human serum albumin nanoparticles to improve its bioavailability. The nanoparticles were prepared by a desolvation method and characterized by spectroscopic and microscopic techniques. The particles were smooth and spherical in nature with an average size of 220 ± 8 nm. The encapsulation efficiency was found to be 84%. The in vitro release profile showed a biphasic pattern and the release rate increases with increase in ionic strength of solution. We have also confirmed the antioxidant activity of the prepared nanoparticles by a DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. Further its anticancer activity was evaluated using MCF-7 breast cancer cell lines. Our findings suggest that fisetin loaded HSA nanoparticles could be used to transfer fisetin to target areas under specific conditions and thus may find use as a delivery vehicle for the flavonoid.

  12. Comparison of distribution and activity of nanoparticles with short interfering DNA (Dbait) in various living systems.

    PubMed

    Berthault, N; Maury, B; Agrario, C; Herbette, A; Sun, J-S; Peyrieras, N; Dutreix, M

    2011-10-01

    Introducing small DNA molecules (Dbait) impairs the repair of damaged chromosomes and provides a new method for enhancing the efficiency of radiotherapy in radio-resistant tumors. The radiosensitizing activity is dependent upon the efficient delivery of Dbait molecules into the tumor cells. Different strategies have been compared, to improve this key step. We developed a pipeline of assays to select the most efficient nanoparticles and administration protocols before preclinical assays: (i) molecular analyses of complexes formed with Dbait molecules, (ii) cellular tests for Dbait uptake and activity, (iii) live zebrafish embryo confocal microscopy monitoring for in vivo distribution and biological activity of the nanoparticles and (iv) tumor growth and survival measurement on mice with xenografted tumors. Two classes of nanoparticles were compared, polycationic polymers with linear or branched polyethylenimine (PEI) and covalently attached cholesterol (coDbait). The most efficient Dbait transfection was observed with linear PEI complexes, in vitro and in vivo. Doses of coDbait ten-fold higher than PEI/Dbait nanoparticles, and pretreatment with chloroquine, were required to obtain the same antitumoral effect on xenografted melanoma. However, with a 22-fold lower 'efficacy dose/toxicity dose' ratio as compared with Dbait/PEI, coDbait was selected for clinical trials.

  13. Development and evaluation of antimicrobial activated carbon fiber filters using Sophora flavescens nanoparticles.

    PubMed

    Sim, Kyoung Mi; Kim, Kyung Hwan; Hwang, Gi Byoung; Seo, SungChul; Bae, Gwi-Nam; Jung, Jae Hee

    2014-09-15

    Activated carbon fiber (ACF) filters have a wide range of applications, including air purification, dehumidification, and water purification, due to their large specific surface area, high adsorption capacity and rate, and specific surface reactivity. However, when airborne microorganisms such as bacteria and fungi adhere to the carbon substrate, ACF filters can become a source of microbial contamination, and their filter efficacy declines. Antimicrobial treatments are a promising means of preventing ACF bio-contamination. In this study, we demonstrate the use of Sophora flavescens in antimicrobial nanoparticles coated onto ACF filters. The particles were prepared using an aerosol process consisting of nebulization-thermal drying and particle deposition. The extract from S. flavescens is an effective, natural antimicrobial agent that exhibits antibacterial activity against various pathogens. The efficiency of Staphylococcus epidermidis inactivation increased with the concentration of S. flavescens nanoparticles in the ACF filter coating. The gas adsorption efficiency of the coated antimicrobial ACF filters was also evaluated using toluene. The toluene-removal capacity of the ACF filters remained unchanged while the antimicrobial activity was over 90% for some nanoparticle concentrations. Our results provide a scientific basis for controlling both bioaerosol and gaseous pollutants using antimicrobial ACF filters coated with S. flavescens nanoparticles.

  14. Emulsification-Induced Homohelicity in Racemic Helical Polymer for Preparing Optically Active Helical Polymer Nanoparticles.

    PubMed

    Zhao, Biao; Deng, Jinrui; Deng, Jianping

    2016-04-01

    Optically active nano- and microparticles have constituted a significant category of advanced functional materials. However, constructing optically active particles derived from synthetic helical polymers still remains as a big challenge. In the present study, it is attempted to induce a racemic helical polymer (containing right- and left-handed helices in equal amount) to prefer one predominant helicity in aqueous media by using emulsifier in the presence of chiral additive (emulsification process). Excitingly, the emulsification process promotes the racemic helical polymer to unify the helicity and directly provides optically active nanoparticles constructed by chirally helical polymer. A possible mechanism is proposed to explain the emulsification-induced homohelicity effect. The present study establishes a novel strategy for preparing chirally helical polymer-derived optically active nanoparticles based on racemic helical polymers.

  15. Mycosynthesis: antibacterial, antioxidant and antiproliferative activities of silver nanoparticles synthesized from Inonotus obliquus (Chaga mushroom) extract.

    PubMed

    Nagajyothi, P C; Sreekanth, T V M; Lee, Jae-il; Lee, Kap Duk

    2014-01-05

    In the present study, silver nanoparticles (AgNPs) were rapidly synthesized from silver nitrate solution at room temperature using Inonotus obliquus extract. The mycogenic synthesized AgNPs were characterized by UV-Visible absorption spectroscopy, Fourier transform infrared (FTIR), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). SEM revealed mostly spherical nanoparticles ranging from 14.7 to 35.2nm in size. All AgNPs concentrations showed good ABT radical scavenging activity. Further, AgNPs showed effective antibacterial activity against both gram negative and gram positive bacteria and antiproliferative activity toward A549 human lung cancer (CCL-185) and MCF-7 human breast cancer (HTB-22) cell lines. The samples demonstrated considerably high antibacterial, and antiproliferative activities against bacterial strains and cell lines.

  16. Seaweed-mediated biosynthesis of silver nanoparticles using Gracilaria corticata for its antifungal activity against Candida spp.

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Senthamil Selvi, S.; Govindaraju, M.

    2013-12-01

    The present study was demonstrated with simple and rapid synthesis of silver (Ag) nanoparticles using marine seaweed, Gracilaria corticata. The visibility of prominent color change at 60 °C within 20 min indicates the formation of Ag nanoparticles. The synthesized Ag nanoparticles were well characterized by UV-vis spectrum, Fourier infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and dynamic light scattering measurements (DLS). Prominent FTIR peaks were obtained corresponding to phenolic compounds, amide I group and aromatic rings which involved in the stabilization of Ag nanoparticles. G. corticata resulted in spherical shaped nanospheres of 18-46 nm as revealed by TEM. The average size distributions of Ag nanoparticles were 51.82 nm and are fairly stable with a zeta potential value of -26.2 mV. The result showed that, biosynthesized Ag nanoparticles from G. corticata have an effective antifungal activity against Candida albicans and C. glabrata.

  17. Green synthesis of silver nanoparticles using Alternanthera dentata leaf extract at room temperature and their antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Kumar, Deenadayalan Ashok; Palanichamy, V.; Roopan, Selvaraj Mohana

    2014-06-01

    A green rapid biogenic synthesis of silver nanoparticles AgNPs using Alternanthera dentata (A. dentata) aqueous extract was demonstrated in this present study. The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance (SPR) at 430 nm using UV-visible spectrophotometer. The reduction of silver ions to silver nanoparticles by A. dentata extract was completed within 10 min. Synthesized nanoparticles were characterized using UV-visible spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). The extracellular silver nanoparticles synthesis by aqueous leaf extract demonstrates rapid, simple and inexpensive method comparable to chemical and microbial methods. The colloidal solution of silver nanoparticles were found to exhibit antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and, Enterococcus faecalis.

  18. Biosynthesis and characterization of Acalypha indica mediated copper oxide nanoparticles and evaluation of its antimicrobial and anticancer activity

    NASA Astrophysics Data System (ADS)

    Sivaraj, Rajeshwari; Rahman, Pattanathu K. S. M.; Rajiv, P.; Narendhran, S.; Venckatesh, R.

    2014-08-01

    Copper oxide nanoparticles were synthesized by biological method using aqueous extract of Acalypha indica leaf and characterized by UV-visible spectroscopy, XRD, FT-IR, SEM TEM and EDX analysis. The synthesised particles were highly stable, spherical and particle size was in the range of 26-30 nm. The antimicrobial activity of A.indica mediated copper oxide nanoparticles was tested against selected pathogens. Copper oxide nanoparticles showed efficient antibacterial and antifungal effect against Escherichia coli, Pseudomonas fluorescens and Candida albicans. The cytotoxicity activity of A.indica mediated copper nanoparticles was evaluated by MTT assay against MCF-7 breast cancer cell lines and confirmed that copper oxide nanoparticles have cytotoxicity activity.

  19. A strong support-effect on the catalytic activity of gold nanoparticles for hydrogen peroxide decomposition.

    PubMed

    Naya, Shin-ichi; Teranishi, Miwako; Kimura, Keisuke; Tada, Hiroaki

    2011-03-21

    Catalytic activity of gold nanoparticle (NP)-loaded metal oxide semiconductors (Au/MOs) for H(2)O(2) decomposition and chemoselective oxidation of cinnamyl alcohol to cinnamaldehyde strongly depends on both the kind of the MO-supports and the Au particle size, and Au/SrTiO(3) exhibits an extraordinary high level of activity for the H(2)O(2) decomposition exceeding that of Pt/TiO(2).

  20. Visible photocatalytic and photoelectrochemical activities of TiO2 nanobelts modified by In2O3 nanoparticles.

    PubMed

    Yang, Hongru; Tian, Jian; Bo, Yanyan; Zhou, Yanli; Wang, Xinzhen; Cui, Hongzhi

    2017-02-01

    Novel In2O3 nanoparticle/TiO2 nanobelt heterostructures with enhanced visible-light photocatalytic and photoelectrochemical (PEC) performance were successfully prepared via a facile hydrothermal method. Well-dispersed In2O3 nanoparticles with small sizes are uniformly attached on the surface of TiO2 nanobelts to form In2O3 nanoparticle/TiO2 nanobelt heterostructures. The TiO2 nanobelts as backbones restrict the aggregation of In2O3 nanoparticles, resulting in the formation of smaller In2O3 nanoparticles with more interaction sites for pollutants. The visible photocatalytic activity of as-prepared heterostructures for degradation of methyl blue (MB) is higher than those of TiO2 nanobelts and In2O3 nanoparticles alone. Moreover, the In2O3 nanoparticle/TiO2 nanobelt heterostructure shows an enhanced PEC performance under irradiation of visible light. The enhanced photocatalytic and PEC activities are mainly ascribed to the synergic effect of efficient charge separation of heterostructure, visible-light harvesting ability of In2O3, and the formation of preferential adsorption sites by the small size of In2O3 nanoparticles. Finally, based on the experimental results of Mott-Schottky, UV-vis DRS, photocurrent and open-circuit voltage response, a possible photocatalytic mechanism over the In2O3 nanoparticle/TiO2 nanobelt heterostructure is proposed.

  1. Removal of Trichloroethylene by Activated Carbon in the Presence and Absence of TiO2 Nanoparticles

    EPA Science Inventory

    Nanoparticles (NPs) are emerging as a new type of contaminant in water and wastewater. The fate of titanium dioxide nanoparticles (TiO2NPs) in a granular activated carbon (GAC) adsorber and their impact on the removal of trichloroethylene (TCE) by GAC was investigated...

  2. Activators generated by electron transfer for atom transfer radical polymerization of styrene in the presence of mesoporous silica nanoparticles

    SciTech Connect

    Khezri, Khezrollah; Roghani-Mamaqani, Hossein

    2014-11-15

    Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presence of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric

  3. Understanding the Adsorption Interface of Polyelectrolyte Coating on Redox Active Nanoparticles Using Soft Particle Electrokinetics and Its Biological Activity

    PubMed Central

    2015-01-01

    The application of cerium oxide nanoparticles (CNPs) for therapeutic purposes requires a stable dispersion of nanoparticles in a biological environment. The objective of this study is to tailor the properties of polyelectrolyte coated CNPs as a function of molecular weight to achieve a stable and catalytic active dispersion. The coating of CNPs with polyacrylic acid (PAA) has increased the dispersion stability of CNPs and enhanced the catalytic ability. The stability of PAA coating was analyzed using the change in the Gibbs free energy computed by the Langmuir adsorption model. The adsorption isotherms were determined using soft particle electrokinetics which overcomes the challenges presented by other techniques. The change in Gibbs free energy was highest for CNPs coated with PAA of 250 kg/mol indicating the most stable coating. The change in free energy for PAA of 100 kg/mol coated CNPs was 85% lower than the PAA of 250 kg/mol coated CNPs. This significant difference is caused by the strong adsorption of PAA of 100 kg/mol on CNPs. Catalytic activity of PAA-CNPs is assessed by the catalase enzymatic mimetic activity of nanoparticles. The catalase activity was higher for PAA coated CNPs as compared to bare CNPs which indicated preferential adsorption of hydrogen peroxide induced by coating. This indicates that the catalase activity is also affected by the structure of the coating layer. PMID:24673655

  4. Antiproliferative effect of Antrodia camphorata polysaccharides encapsulated in chitosan-silica nanoparticles strongly depends on the metabolic activity type of the cell line

    NASA Astrophysics Data System (ADS)

    Kong, Zwe-Ling; Chang, Jenq-Sheng; Chang, Ke Liang B.

    2013-09-01

    Chitosan molecules interact with silica and encapsulate the Antrodia camphorata extract (ACE) polysaccharides to form composite nanoparticles. The nanoparticle suspensions of ACE polysaccharides encapsulated in silica-chitosan and silica nanoparticles approach an average particle size of 210 and 294 nm in solution, respectively. The encapsulation efficiencies of ACE polysaccharides are 66 and 63.5 %, respectively. Scanning electron micrographs confirm the formation of near-spherical nanoparticles. ACE polysaccharides solution had better antioxidative capability than ACE polysaccharides encapsulated in silica or silica-chitosan nanoparticles suspensions. The antioxidant capacity of nanoparticles increases with increasing dissolution time. The antitumor effects of ACE polysaccharides, ACE polysaccharides encapsulated in silica, or silica-chitosan nanoparticles increased with increasing concentration of nanoparticles. This is the first report demonstrating the potential of ACE polysaccharides encapsulated in chitosan-silica nanoparticles for cancer chemoprevention. Furthermore, this study suggests that antiproliferative effect of nanoparticle-encapsulated bioactive could significantly depend on the metabolic activity type of the cell line.

  5. Hydrogen peroxide sensing and cytotoxicity activity of Acacia lignin stabilized silver nanoparticles.

    PubMed

    Aadil, Keshaw Ram; Barapatre, Anand; Meena, Avtar Singh; Jha, Harit

    2016-01-01

    The study is aimed at detection of hydrogen peroxide (H2O2) using Acacia lignin mediated silver nanoparticles (AGNPs). The synthesis of AGNPs was achieved at conditions optimized as, 3 ml of 0.02% lignin and 1mM silver nitrate incubated for 30 min at 80°C and pH 9. Initial screening of AGNPs was performed by measuring the surface plasmon resonance peak at 410-430 nm using UV-vis spectrophotometer. Transmission electron microscopy, atomic force microscopy, X-ray diffraction and particle size analysis confirmed the spherical shaped face centered cubic structure and 10-50 nm size of AGNPs. The infrared spectroscopy study further revealed that the active functional groups present in lignin were responsible for the reduction of silver ions (Ag(+)) to metallic silver (Ag(0)). Lignin stabilized silver nanoparticles showed good sensitivity and a linear response over wide concentrations of H2O2 (10(-1) to 10(-6)M). Further, the in vitrocytotoxicity activity of the lignin mediated AGNPs (5-500 μg/ml) demonstrated toxicity effects in MCF-7 and A375 cell lines. Thus, lignin stabilized silver nanoparticles based optical sensor for H2O2 could be potentially applied in the determination of reactive oxygen species and toxic chemicals which further expands the importance of lignin stabilized silver nanoparticles.

  6. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling.

    PubMed

    Chaudhary, V; Ramanujan, R V

    2016-10-11

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100-xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg(-1). Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

  7. Spectroscopy study of silver nanoparticles fabrication using synthetic humic substances and their antimicrobial activity.

    PubMed

    Litvin, Valentina A; Minaev, Boris F

    2013-05-01

    In this present study, silver nanoparticles were synthesized using synthetic humic substances (HSs) as reducing and stabilizing agents. Preference of synthetic HSs over natural humic matter is determined by a standardization problem resolution of the product due to the strict control of conditions of the synthetic HSs formation. It allows to receive the silver nanoparticles with the standardized biologically-active protective shell that is very important for their use, mainly in medicine. The concentration of sodium hydroxide, synthetic HSs, silver nitrate and temperature employed in the synthesis process are optimized to attain better yield, controlled size and stability by means of UV-visible technique. In the optimal reaction conditions the concentrated silver colloids (55 mM) with 99.99% yield are obtained which were stable for more than 1 year under ambient conditions. The received silver nanoparticles are characterized by UV-visible spectroscopy, X-ray diffraction (XRD), FT-IR spectroscopy and transmission electron microscopy (TEM). The antimicrobial activity of silver nanoparticles against fungal and bacterial strains is also shown.

  8. Spectroscopy study of silver nanoparticles fabrication using synthetic humic substances and their antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Litvin, Valentina A.; Minaev, Boris F.

    2013-05-01

    In this present study, silver nanoparticles were synthesized using synthetic humic substances (HSs) as reducing and stabilizing agents. Preference of synthetic HSs over natural humic matter is determined by a standardization problem resolution of the product due to the strict control of conditions of the synthetic HSs formation. It allows to receive the silver nanoparticles with the standardized biologically-active protective shell that is very important for their use, mainly in medicine. The concentration of sodium hydroxide, synthetic HSs, silver nitrate and temperature employed in the synthesis process are optimized to attain better yield, controlled size and stability by means of UV-visible technique. In the optimal reaction conditions the concentrated silver colloids (55 mM) with 99.99% yield are obtained which were stable for more than 1 year under ambient conditions. The received silver nanoparticles are characterized by UV-visible spectroscopy, X-ray diffraction (XRD), FT-IR spectroscopy and transmission electron microscopy (TEM). The antimicrobial activity of silver nanoparticles against fungal and bacterial strains is also shown.

  9. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    NASA Astrophysics Data System (ADS)

    Chaudhary, V.; Ramanujan, R. V.

    2016-10-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100‑xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg‑1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

  10. Green synthesis of copper nanoparticles by Citrus medica Linn. (Idilimbu) juice and its antimicrobial activity.

    PubMed

    Shende, Sudhir; Ingle, Avinash P; Gade, Aniket; Rai, Mahendra

    2015-06-01

    We report an eco-friendly method for the synthesis of copper nanoparticles (CuNPs) using Citron juice (Citrus medica Linn.), which is nontoxic and cheap. The biogenic copper nanoparticles were characterized by UV-Vis spectrophotometer showing a typical resonance (SPR) at about 631 nm which is specific for CuNPs. Nanoparticles tracking analysis by NanoSight-LM20 showed the particles in the range of 10-60 nm with the concentration of 2.18 × 10(8) particles per ml. X-ray diffraction revealed the FCC nature of nanoparticles with an average size of 20 nm. The antimicrobial activity of CuNPs was determined by Kirby-Bauer disk diffusion method against some selected species of bacteria and plant pathogenic fungi. It was reported that the synthesized CuNPs demonstrated a significant inhibitory activity against Escherichia coli followed by Klebsiella pneumoniae, Pseudomonas aeruginosa, Propionibacterium acnes and Salmonella typhi. Among the plant pathogenic fungi tested, Fusarium culmorum was found to be most sensitive followed by F. oxysporum and F. graminearum. The novelty of this work is that for the first time citron juice was used for the synthesis of CuNPs.

  11. Colloidally stable surface-modified iron oxide nanoparticles: Preparation, characterization and anti-tumor activity

    NASA Astrophysics Data System (ADS)

    Macková, Hana; Horák, Daniel; Donchenko, Georgiy Viktorovich; Andriyaka, Vadim Ivanovich; Palyvoda, Olga Mikhailovna; Chernishov, Vladimir Ivanovich; Chekhun, Vasyl Fedorovich; Todor, Igor Nikolaevich; Kuzmenko, Oleksandr Ivanovich

    2015-04-01

    Maghemite (γ-Fe2O3) nanoparticles were obtained by co-precipitation of Fe(II) and Fe(III) chlorides and subsequent oxidation with sodium hypochlorite and coated with poly(N,N-dimethylacrylamide-co-acrylic acid) [P(DMAAm-AA)]. They were characterized by a range of methods including transmission electron microscopy (TEM), elemental analysis, dynamic light scattering (DLS) and zeta potential measurements. The effect of superparamagnetic P(DMAAm-AA)-γ-Fe2O3 nanoparticles on oxidation of blood lipids, glutathione and proteins in blood serum was detected using 2-thiobarbituric acid and the ThioGlo fluorophore. Finally, mice received magnetic nanoparticles administered per os and the antitumor activity of the particles was tested on Lewis lung carcinoma (LLC) in male mice line C57BL/6 as an experimental in vivo metastatic tumor model; the tumor size was measured and the number of metastases in lungs was determined. Surface-modified γ-Fe2O3 nanoparticles showed higher antitumor and antimetastatic activities than commercial CuFe2O4 particles and the conventional antitumor agent cisplatin.

  12. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    PubMed Central

    Chaudhary, V.; Ramanujan, R.V.

    2016-01-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100−xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg−1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications. PMID:27725754

  13. Selective Electrocatalytic Activity of Ligand Stabilized Copper Oxide Nanoparticles

    SciTech Connect

    Kauffman, Douglas R; Ohodnicki, Paul R; Kail, Brian W; Matranga, Christopher

    2011-01-01

    Ligand stabilization can influence the surface chemistry of Cu oxide nanoparticles (NPs) and provide unique product distributions for electrocatalytic methanol (MeOH) oxidation and CO{sub 2} reduction reactions. Oleic acid (OA) stabilized Cu{sub 2}O and CuO NPs promote the MeOH oxidation reaction with 88% and 99.97% selective HCOH formation, respectively. Alternatively, CO{sub 2} is the only reaction product detected for bulk Cu oxides and Cu oxide NPs with no ligands or weakly interacting ligands. We also demonstrate that OA stabilized Cu oxide NPs can reduce CO{sub 2} into CO with a {approx}1.7-fold increase in CO/H{sub 2} production ratios compared to bulk Cu oxides. The OA stabilized Cu oxide NPs also show 7.6 and 9.1-fold increases in CO/H{sub 2} production ratios compared to weakly stabilized and non-stabilized Cu oxide NPs, respectively. Our data illustrates that the presence and type of surface ligand can substantially influence the catalytic product selectivity of Cu oxide NPs.

  14. Anti-angiogenic activity of heparin functionalised cerium oxide nanoparticles.

    PubMed

    Lord, Megan S; Tsoi, Bonny; Gunawan, Cindy; Teoh, Wey Yang; Amal, Rose; Whitelock, John M

    2013-11-01

    Cerium oxide nanoparticles (nanoceria) are widely reported to be non-cytotoxic and modulate intracellular reactive oxygen species (ROS). In this study, nanoceria (dxRD = 12 nm) were functionalised with either 130 or 880 molecules of unfractionated heparin using the organosilane linker, 3-aminopropyltriethoxysilane. Nanoceria with a low level of heparin functionalisation were found to scavenge intracellular ROS to the same extent as unfunctionalised nanoceria and significantly more than cells exposed to medium only. In contrast, nanoceria with the highest level of heparin functionalisation were not as effective at scavenging intracellular ROS. Nanoceria were localised predominantly in the cytoplasm, while heparin-nanoceria were localised in both the cytoplasm and lysosomes. Together these data demonstrated that the level of nanoceria surface functionalisation with heparin determined the intracellular localisation and ROS scavenging ability of these particles. Additionally, heparin-nanoceria were effective in reducing endothelial cell proliferation indicating that they may find application in the control of angiogenesis in cancer in the future.

  15. Facile synthesis of PtAu alloy nanoparticles with high activity for formic acid oxidation

    SciTech Connect

    Zhang, Sheng; Shao, Yuyan; Yin, Geping; Lin, Yuehe

    2010-02-15

    We report the facile synthesis of carbon supported PtAu alloy nanoparticles with high electrocatalytic activity as the anode catalyst for direct formic acid fuel cells (DFAFCs). PtAu alloy nanopaticles are synthesized by co-reducing HAuCl4 and H2PtCl6 with NaBH4 in the presence of sodium citrate and then the nanoparticles are deposited on Vulcan XC-72R carbon support (PtAu/C). The obtained catalysts are characterized with X-ray diffraction (XRD) and transmission electron microscope (TEM), which reveal PtAu alloy formation with an average diameter of 4.6 nm. PtAu/C exhibits 8 times higher catalytic activity toward formic acid oxidation than Pt/C. The enhanced activity of PtAu/C catalyst is attributed to noncontinuous Pt sites formed in the presence of the neighbored Au sites, which promotes direct oxidation of formic acid by avoiding poison CO.

  16. Targeting inflammasome by the inhibition of caspase-1 activity using capped mesoporous silica nanoparticles.

    PubMed

    García-Fernández, Alba; García-Laínez, Guillermo; Ferrándiz, María Luisa; Aznar, Elena; Sancenón, Félix; Alcaraz, María José; Murguía, José Ramón; Marcos, María D; Martínez-Máñez, Ramón; Costero, Ana M; Orzáez, Mar

    2017-02-28

    Acute inflammation is a protective response of the body to harmful stimuli, such as pathogens or damaged cells. However, dysregulated inflammation can cause secondary damage and could thus contribute to the pathophysiology of many diseases. Inflammasomes, the macromolecular complexes responsible for caspase-1 activation, have emerged as key regulators of immune and inflammatory responses. Therefore, modulation of inflammasome activity has become an important therapeutic approach. Here we describe the design of a smart nanodevice that takes advantage of the passive targeting of nanoparticles to macrophages and enhances the therapeutic effect of caspase-1 inhibitor VX-765 in vivo. The functional hybrid systems consisted of MCM-41-based nanoparticles loaded with anti-inflammatory drug VX-765 (S2-P) and capped with poly-L-lysine, which acts as a molecular gate. S2-P activity has been evaluated in cellular and in vivo models of inflammation. The results indicated the potential advantage of using nanodevices to treat inflammatory diseases.

  17. Photochemical Synthesis of Shape-Controlled Nanostructured Gold on Zinc Oxide Nanorods as Photocatalytically Renewable Sensors.

    PubMed

    Xu, Jia-Quan; Duo, Huan-Huan; Zhang, Yu-Ge; Zhang, Xin-Wei; Fang, Wei; Liu, Yan-Ling; Shen, Ai-Guo; Hu, Ji-Ming; Huang, Wei-Hua

    2016-04-05

    Biosensors always suffer from passivation that prevents their reutilization. To address this issue, photocatalytically renewable sensors composed of semiconductor photocatalysts and sensing materials have emerged recently. In this work, we developed a robust and versatile method to construct different kinds of renewable biosensors consisting of ZnO nanorods and nanostructured Au. Via a facile and efficient photochemical reduction, various nanostructured Au was obtained successfully on ZnO nanorods. As-prepared sensors concurrently possess excellent sensing capability and desirable photocatalytic cleaning performance. Experimental results demonstrate that dendritic Au/ZnO composite has the strongest surface-enhanced Raman scattering (SERS) enhancement, and dense Au nanoparticles (NPs)/ZnO composite has the highest electrochemical activity, which was successfully used for electrochemical detection of NO release from cells. Furthermore, both of the SERS and electrochemical sensors can be regenerated efficiently for renewable applications via photodegrading adsorbed probe molecules and biomolecules. Our strategy provides an efficient and versatile method to construct various kinds of highly sensitive renewable sensors and might expand the application of the photocatalytically renewable sensor in the biosensing area.

  18. Antioxidant and anti-inflammatory activities of silver nanoparticles biosynthesized from aqueous leaves extracts of four Terminalia species

    NASA Astrophysics Data System (ADS)

    El-Rafie, Hanaa Mohamed; Abdel-Aziz Hamed, Manal

    2014-09-01

    The environmentally friendly synthesis of nanoparticles process is a revolutionary step in the field of nanotechnology. In recent years plant mediated biological synthesis of nanoparticles has been gaining importance due to its simplicity and eco-friendliness. In this study, a simple and an efficient eco-friendly approach for the biosynthesis of stable, monodisperse silver nanoparticles using aqueous extracts of four Terminalia species, namely, Terminalia catappa, Terminalia mellueri, Terminalia bentazoe and Terminalia bellerica were described. The silver nanoparticles were characterized in terms of synthesis, capping functionalities (polysaccharides, phenolics and flavonoidal compounds) and microscopic evaluation by UV-visible spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. The results showed a simple and feasible approach for obtaining stable aqueous monodispersive silver nanoparticles. Furthermore, biological activity of the biosynthesized silver nanoparticles was examined. Concerning this, dose-dependent antioxidant activity of silver nanoparticles imparted by the plant phenolic and flavonoidal components was evaluated using in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and found to be comparable to standard ascorbic acid. The same holds true for the anti-inflammatory activity where Terminalia catappa and Terminalia mellueri have a high-test inhibition percentage better than that of ascorbic acid in the carrageenan induced hind paw edema. The results also revealed that the aqueous extract of Terminallia catapa and its silver nanoparticles recorded the most potent in vivo antioxidant effect.

  19. Suppressing photochemical reactions with quantized light fields

    NASA Astrophysics Data System (ADS)

    Galego, Javier; Garcia-Vidal, Francisco J.; Feist, Johannes

    2016-12-01

    Photoisomerization, that is, a photochemical reaction leading to a change of molecular structure after absorption of a photon, can have detrimental effects such as leading to DNA damage under solar irradiation, or as a limiting factor for the efficiency of solar cells. Here, we show that strong coupling of organic molecules to a confined light mode can be used to strongly suppress photoisomerization, as well as other photochemical reactions, and thus convert molecules that normally show fast photodegradation into photostable forms. We find this to be especially efficient in the case of collective strong coupling, where the distribution of a single excitation over many molecules and the light mode leads to a collective protection effect that almost completely suppresses the photochemical reaction.

  20. Suppressing photochemical reactions with quantized light fields

    PubMed Central

    Galego, Javier; Garcia-Vidal, Francisco J.; Feist, Johannes

    2016-01-01

    Photoisomerization, that is, a photochemical reaction leading to a change of molecular structure after absorption of a photon, can have detrimental effects such as leading to DNA damage under solar irradiation, or as a limiting factor for the efficiency of solar cells. Here, we show that strong coupling of organic molecules to a confined light mode can be used to strongly suppress photoisomerization, as well as other photochemical reactions, and thus convert molecules that normally show fast photodegradation into photostable forms. We find this to be especially efficient in the case of collective strong coupling, where the distribution of a single excitation over many molecules and the light mode leads to a collective protection effect that almost completely suppresses the photochemical reaction. PMID:27941754

  1. Stratospheric Ozone: Transport, Photochemical Production and Loss

    NASA Technical Reports Server (NTRS)

    Douglass, A. R.; Kawa, S. R.; Jackman, C. H.

    2003-01-01

    Observations from various satellite instruments (e.g., Total Ozone Mapping Spectrometer (TOMS), Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS)) specify the latitude and seasonal variations of total ozone and ozone as a function of altitude. These seasonal variations change with latitude and altitude partly due to seasonal variation in transport and temperature, partly due to differences in the balance between photochemical production and loss processes, and partly due to differences in the relative importance of the various ozone loss processes. Comparisons of modeled seasonal ozone behavior with observations test the following: the seasonal dependence of dynamical processes where these dominate the ozone tendency; the seasonal dependence of photochemical processes in the upper stratosphere; and the seasonal change in the balance between photochemical and dynamical processes.

  2. Enhancing the tumor discrimination using antibody-activated magnetic nanoparticles in ultra-low magnetic fields

    NASA Astrophysics Data System (ADS)

    Yang, H. C.; Huang, K. W.; Liao, S. H.; Horng, H. E.; Chieh, J. J.; Chen, H. H.; Chen, M. J.; Chen, K. L.; Wang, L. M.

    2013-01-01

    In this paper, we report an enhanced liver tumor discrimination for rats using antibody-activated magnetic nanoparticles (MNs) and ultra-low-field magnetic resonance imaging ex vivo. It was found that the intensity ratio between the magnetic resonance image of tumor and normal liver tissues is 2-3 absence of antibody-activated MNs in rats. The intensity ratio rises to ˜100 when antibody-activated MNs are expressed in liver tumors through vein injection. Enhancing tumor discrimination using antibody-activated MNs is demonstrated using T1-weighted contrast imaging in ultra-low magnetic fields.

  3. Synthesis of N-halamine-functionalized silica-polymer core-shell nanoparticles and their enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Dong, Alideertu; Huang, Jinfeng; Lan, Shi; Wang, Tao; Xiao, Linghan; Wang, Weiwei; Zhao, Tianyi; Zheng, Xin; Liu, Fengqi; Gao, Ge; Chen, Yuxin

    2011-07-01

    N-halamine-functionalized silica-polymer core-shell nanoparticles with enhanced antibacterial activity were synthesized through the encapsulation of silica nanoparticles as support with polymeric N-halamine. The as-synthesized nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive x-ray spectrometry (EDX), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR). These N-halamine-functionalized silica-polymer core-shell nanoparticles displayed powerful antibacterial performance against both Gram-positive bacteria and Gram-negative bacteria, and their antibacterial activities have been greatly improved compared with their bulk counterparts. Therefore, these N-halamine-functionalized silica-polymer core-shell nanoparticles have the potential for various significant applications such as in medical devices, healthcare products, water purification systems, hospitals, dental office equipment, food packaging, food storage, household sanitation, etc.

  4. Assessment of diphenylcyclopropenone for photochemically induced mutagenicity in the Ames assay

    SciTech Connect

    Wilkerson, M.G.; Connor, T.H.; Henkin, J.; Wilkin, J.K.; Matney, T.S.

    1987-10-01

    The photochemical conversion of diphenylcyclopropenone to diphenylacetylene has recently been reported. Diphenylcyclopropenone is used in the treatment of alopecia areata and is nonmutagenic in a limited Ames assay. We examined diphenylcyclopropenone and diphenylacetylene, as well as synthetic precursors of diphenylcyclopropenone--dibenzylketone and alpha,alpha'-dibromodibenzylketone--for mutagenicity against TA100, TA98, TA102, UTH8413, and UTH8414. All compounds were nonmutagenic except alpha,alpha'-dibromodibenzylketone, which was a potent mutagen in TA100 with and without S-9 activation. The effect of photochemical activation of diphenylcyclopropenone in the presence of bacteria demonstrated mutagenicity in UTH8413 (two times background) at 10 micrograms/plate with S-9 microsomal activation. 8-Methoxypsoralen produces a mutagenic response in TA102 at 0.1 microgram/plate with 60 seconds of exposure to 350 nm light. In vitro photochemically activated Ames assay with S-9 microsomal fraction may enhance the trapping of short-lived photochemically produced high-energy mutagenic intermediates. This technique offers exciting opportunities to trap high-energy intermediates that may play an important role in mutagenesis. This method can be applied to a variety of topically applied dermatologic agents, potentially subjected to photochemical changes in normal use.

  5. Silver nanoparticles synthesis mediated by new isolates of Bacillus spp., nanoparticle characterization and their activity against Bean Yellow Mosaic Virus and human pathogens

    PubMed Central

    Elbeshehy, Essam K. F.; Elazzazy, Ahmed M.; Aggelis, George

    2015-01-01

    Extracellular agents produced by newly isolated bacterial strains were able to catalyze the synthesis of silver nanoparticles (AgNPs). The most effective isolates were identified as Bacillus pumilus, B. persicus, and Bacillus licheniformis using molecular identification. DLS analysis revealed that the AgNPs synthesized by the above strains were in the size range of 77–92 nm. TEM observations showed that the nanoparticles were coated with a capping agent, which was probably involved in nanoparticle stabilization allowing their perfect dispersion in aqueous solutions. FTIR analyses indicated the presence of proteins in the capping agent of the nanoparticles and suggested that the oxidation of hydroxyl groups of peptide hydrolysates (originated from the growth medium) is coupled to the reduction of silver ions. Energy Dispersive X-ray Spectroscopy confirmed the above results. The nanoparticles, especially those synthesized by B. licheniformis, were stable (zeta potential ranged from −16.6 to −21.3 mV) and showed an excellent in vitro antimicrobial activity against important human pathogens and a considerable antiviral activity against the Bean Yellow Mosaic Virus. The significance of the particular antiviral activity is highlighted, given the significant yield reduction in fava bean crops resulting from Bean Yellow Mosaic Virus infections, in many African countries. PMID:26029190

  6. Silver nanoparticles synthesis mediated by new isolates of Bacillus spp., nanoparticle characterization and their activity against Bean Yellow Mosaic Virus and human pathogens.

    PubMed

    Elbeshehy, Essam K F; Elazzazy, Ahmed M; Aggelis, George

    2015-01-01

    Extracellular agents produced by newly isolated bacterial strains were able to catalyze the synthesis of silver nanoparticles (AgNPs). The most effective isolates were identified as Bacillus pumilus, B. persicus, and Bacillus licheniformis using molecular identification. DLS analysis revealed that the AgNPs synthesized by the above strains were in the size range of 77-92 nm. TEM observations showed that the nanoparticles were coated with a capping agent, which was probably involved in nanoparticle stabilization allowing their perfect dispersion in aqueous solutions. FTIR analyses indicated the presence of proteins in the capping agent of the nanoparticles and suggested that the oxidation of hydroxyl groups of peptide hydrolysates (originated from the growth medium) is coupled to the reduction of silver ions. Energy Dispersive X-ray Spectroscopy confirmed the above results. The nanoparticles, especially those synthesized by B. licheniformis, were stable (zeta potential ranged from -16.6 to -21.3 mV) and showed an excellent in vitro antimicrobial activity against important human pathogens and a considerable antiviral activity against the Bean Yellow Mosaic Virus. The significance of the particular antiviral activity is highlighted, given the significant yield reduction in fava bean crops resulting from Bean Yellow Mosaic Virus infections, in many African countries.

  7. Antitumor activity of sorafenib-incorporated nanoparticles of dextran/poly(dl-lactide- co-glycolide) block copolymer

    NASA Astrophysics Data System (ADS)

    Kim, Do Hyung; Kim, Min-Dae; Choi, Cheol-Woong; Chung, Chung-Wook; Ha, Seung Hee; Kim, Cy Hyun; Shim, Yong-Ho; Jeong, Young-Il; Kang, Dae Hwan

    2012-01-01

    Sorafenib-incoporated nanoparticles were prepared using a block copolymer that is composed of dextran and poly( DL-lactide- co-glycolide) [Dex bLG] for antitumor drug delivery. Sorafenib-incorporated nanoparticles were prepared by a nanoprecipitation-dialysis method. Sorafenib-incorporated Dex bLG nanoparticles were uniformly distributed in an aqueous solution regardless of the content of sorafenib. Transmission electron microscopy of the sorafenib-incorporated Dex bLG nanoparticles revealed a spherical shape with a diameter < 300 nm. Sorafenib-incorporated Dex bLG nanoparticles at a polymer/drug weight ratio of 40:5 showed a relatively uniform size and morphology. Higher initial drug feeding was associated with increased drug content in nanoparticles and in nanoparticle size. A drug release study revealed a decreased drug release rate with increasing drug content. In an in vitro anti-proliferation assay using human cholangiocarcinoma cells, sorafenib-incorporated Dex bLG nanoparticles showed a similar antitumor activity as sorafenib. Sorafenib-incorporated Dex bLG nanoparticles are promising candidates as vehicles for antitumor drug targeting.

  8. Generation of NiO nanoparticles via pulsed laser ablation in deionised water and their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Khashan, Khawla S.; Sulaiman, Ghassan M.; Hamad, Abubaker H.; Abdulameer, Farah A.; Hadi, Assel

    2017-03-01

    Nickel oxide (NiO) nanoparticles were synthesised by nanosecond laser ablation in deionised water. Spherical NiO nanoparticles with sizes ranging from 2 to 21 nm were produced. The optical absorption spectra of the nanoparticles were measured using UV-VIS spectroscopy, and their size distribution was characterised using transmission electron microscopy (TEM). The crystalline material structures were investigated using X-ray diffraction (XRD). Fourier transform infrared spectroscopy (FTIR) was used to obtain infrared spectra of the samples. The results show that crystalline NiO nanoparticles were produced. The antibacterial activity of the nanoparticles against Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, and Staphylococcus aureus bacteria was then examined. It was found that the NiO nanoparticles have a synergistic effect on inhibiting E. coli and S. aureus growth; this effect was also tested using the well-diffusion method. In this method, NiO nanoparticles at a concentration of 1000 µg ml-1 along with amoxicillin yielded an inhibition zone against E. coli of 14.3 ± 1.15 mm; this zone was 12.6 ± 0.57 mm against S. aureus. Therefore, from the present findings, it can be concluded that the efficiency of inhibiting bacterial growth could be improved by the addition of metal-oxide nanoparticles to amoxicillin in comparison with either pure amoxicillin or pure metal-oxide nanoparticles.

  9. Preparation and in vitro investigation of antigastric cancer activities of carvacrol-loaded human serum albumin nanoparticles.

    PubMed

    Maryam, Keshavarzi; Shakeri, Shahryar; Kiani, Keyhaneh

    2015-10-01

    In this study, carvacrol-loaded human serum albumin (HSA) nanoparticles were developed and characterised. Nanoparticles were prepared by desolvation and emulsion/desolvation methods. Encapsulation efficiency (EE%) and loading capacity (LC%) of nanoparticles prepared by desolvation method were 48.4 and 45.1%, respectively. Carvacrol-loaded nanoparticles had 132±42 nm in diameter with monomodal distribution. Carvacrol-loaded nanoparticles which is prepared by emulsion/desolvation method had EE% and LC% of 32 and 32.3%, respectively, and 230±38 nm in size. The release of carvacrol from nanoparticles was monitored in phosphate-buffered saline (pH=7.4), 100 rpm at 37°C for 10 days. About 21.4% of carvacrol was released after 3 h from nanoparticles that were prepared by desolvation method. In emulsion/desolvation method, 26.8% of total carvacrol was released during 3 h of incubation. Cytotoxicity effect of loaded carvacrol was assessed by 3-[4, 5 dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) test on gastric cancer cells line (AGS). Cell line was exposed to the free carvacrol, unloaded and carvacrol-loaded nanoparticles for 48 h. The half maximal inhibitory concentration (IC50) for free carvacrol, unloaded and carvacrol-loaded HSA nanoparticles were 30, 1070 and 120 µg/ml, respectively. In conclusion, the results of this study showed applications of HSA nanoparticles for entrapment of carvacrol and antigastric cancer activity. Moreover, loading of carvacrol in combination with chemotherapy agents into the HSA nanoparticles may treat cancer cells better than single drug loaded nanoparticles.

  10. Study of the photochemically generated of oxygen species by fullerene photosensitized CoS{sub 2} nanocompounds

    SciTech Connect

    Meng, Ze-Da; Zhu, Lei; Ullah, Kefayat; Ye, Shu; Sun, Qian; Jang, Won Kweon; Oh, Won-Chun

    2014-01-01

    Graphical abstract: - Highlights: • Reactive oxygen species was detected through oxidation reaction from DPCI to DPCO. • Generated reactive oxygen species and hydroxyl radicals can be analysis by DPCI degradation. • C{sub 60} has good effect during the photo-degradation processes. • Photocatalytic activity attributed to photo-absorption effect by C{sub 60} and cooperative effect of CoS{sub 2}. - Abstract: Reactive oxygen species (ROS) can be produced by interactions between sunlight and light-absorbing substance in natural water environment and can completely destroy various organic pollutants in wastewaters. In this study, CoS{sub 2} and CoS{sub 2}–fullerene were irradiated by visible light respectively. The generation of reactive oxygen species were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). In comparison with the separate effects of CoS{sub 2} and fullerene nanoparticles, the photochemically effect of the fullerene photosensitized CoS{sub 2} composites is increased significantly due to the synergetic effect between the fullerene and the CoS{sub 2} nanoparticles.

  11. Formation and inhibition of photochemical smog

    SciTech Connect

    Heicklen, J.

    1987-01-01

    Photochemical smog is caused by a free-radical chain mechanism which converts NO to NO/sub 2/. The NO/sub 2/ further reacts to produce ozone, nitric acid, and peracylnitrates. This chain mechanism can be inhibited by suitable free-radical scavengers. The chemistry and toxicology of one such free-radical scavenger, diethylhydroxylamine, has been studied in depth. It has been shown to be effective, safe, and practical for use in urban atmospheres to prevent photochemical smog formation. 42 references.

  12. Isatis tinctoria mediated synthesis of amphotericin B-bound silver nanoparticles with enhanced photoinduced antileishmanial activity: A novel green approach.

    PubMed

    Ahmad, Aftab; Wei, Yun; Syed, Fatima; Khan, Shafiullah; Khan, Gul Majid; Tahir, Kamran; Khan, Arif Ullah; Raza, Muslim; Khan, Faheem Ullah; Yuan, Qiping

    2016-08-01

    After malaria, Leishmaniasis is the most prevalent infectious disease in terms of fatality and geographical distribution. The availability of a limited number of antileishmanial agents, emerging resistance to the available drugs, and the high cost of treatment complicate the treatment of leishmaniasis. To overcome these issues, critical research for new therapeutic agents with enhanced antileishmanial potential and low treatment cost is needed. In this contribution, we developed a green protocol to prepare biogenic silver nanoparticles (AgNPs) and amphotericin B-bound biogenic silver nanoparticles (AmB-AgNPs). Phytochemicals from the aqueous extract of Isatis tinctoria were used as reducing and capping agents to prepare silver nanoparticles. Amphotericin B was successfully adsorbed on the surface of biogenic silver nanoparticles. The prepared nanoparticles were characterized by various analytical techniques. UV-Visible spectroscopy was employed to detect the characteristic localized surface plasmon resonance peaks (LSPR) for the prepared nanoparticles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) studies revealed the formation of spherical silver nanoparticles with an average particle size of 10-20nm. The cubic crystalline structure of the prepared nanoparticles was confirmed by X-ray diffraction (XRD) study. FTIR spectroscopic analysis revealed that plant polyphenolic compounds are mainly involved in metal reduction and capping. Under visible light irradiation, biogenic silver nanoparticles exhibited significant activity against Leishmania tropica with an IC50 value of 4.2μg/mL. The leishmanicidal activity of these nanoparticles was considerably enhanced by conjugation with amphotericin B (IC50=2.43μg/mL). In conclusion, the findings of this study reveal that adsorption of amphotericin B, an antileishmanial drug, to biogenic silver nanoparticles, could be a safe, more effective and economic alternative to the available

  13. Dielectric behavior, conduction and EPR active centres in BiVO4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Venkatesan, Rajalingam; Velumani, Subramaniam; Tabellout, Mohamed; Errien, Nicolas; Kassiba, Abdelhadi

    2013-12-01

    Bismuth vanadate (BiVO4) nanomaterials were synthesized by mechano-chemical ball milling method and complementary investigations were devoted to their structures, nanoparticle morphologies and electronic active centres. The dielectric and conductivity behaviour were analysed systematically in wide temperature and frequency ranges to correlate such physical respo